Resorting to more desperate measures to catch Fran cheating, Sam also sends a telegram to an associate in Paris to keep an eye on the whereabouts of Iselin. On the steam ship to Europe, Sam receives a wireless message that Iselin is in Biarritz (in southern France, near the Spanish border): "a fashionable watering place." When Sam is greeted by Fran at the Paris train station after disembarking from the ship, she mentions casually that she has just arrived from Biarritz. He asks: "Weren't you pretty lonely in Biarritz?" She lies: "I wasn't sorry to be by myself for a bit." Sam responds by acting coldly and as a stranger to her. To his surprise, Fran has ordered a two-bedroom suite for them, and they are to sleep in separate rooms.

Sam has also arranged to have her paramour Arnold Iselin meet them in the hotel room. When he arrives, Sam becomes accusatory:

I wanted to see you two face-to-face. Fran alone would have wasted time acting. I knew you'd been in Biarritz together. I'm sorry, Fran. I hate undercover work myself, but I wouldn't have got where I have in this world if it hadn't been for me to be a bit ruthless on occasion.

Iselin interjects: "Shakespeare's Othello ends badly for the hero." Sam states he wants "peace of mind" about their ongoing affair: "I want to hold onto you if I can. You want to marry each other?...You want to divorce me, then?" His confrontation forces Iselin to excuse himself and end their extra-marital relationship. Fran is very sorry for her indiscretions, when Sam offers: "I'm ready to wipe the slate clean, if you are and start out on a long hike tomorrow." He proposes traveling throughout Europe with her, and then returning to Zenith in December about five months later, to coincide with the timing of the birth of Emily's first baby: "We'll have to learn to behave ourselves when we'll be a couple of old grandparents in December."

When the baby boy (named after Sam) arrives in December, the "grandparents" (in Vienna) send a congratulatory cable. Sam and Fran are reconciled and still love each other. Guilt (and being found out) seem to have driven Fran back to Sam, and she admits she has been "so silly and heedless." "I want you back for my wife," Sam tells Fran. However, she then bargains with him - she will officially remain his wife if allowed to stay on in Europe, to continue enjoying youthful pursuits without him. Her fear of getting old has been heightened by the birth of a baby in the family, making her a grandmother (a fact she fears Sam will mention to embarrass her):

Shall I tell you how? By understanding, by staying on here in Europe, by helping me forget Arnold Iselin. By forgetting him yourself...All my friends here think of me as young, and I am. Oh, I am. I was such a child when you married me. It isn't fair.

In Vienna, the flirtatious Fran has begun to associate again with young nobleman Kurt von Obersdorf. Sam declines their invitation to join them for dinner and dancing: "What fun do you think it is for me to sit up all night watching you two dance...I'd only spoil your fun tonight." After "fun and friends all evening," the two return to Fran's hotel suite (Sam is sleeping and "dead to the world"), where Kurt confesses his love for Fran: "I think you could love me, Fran. I think you could," but they realize that they are restricted by her marital status (Fran: "There's nothing we can do about it, is there?"). Kurt is disconsolate: "I can't ask you to be my wife...Why are you not free?" They passionately kiss as he leaves.

During a late-night discussion at her bedroom door, Sam states that he doesn't want to see another affair in the making with Kurt. He insists that they both return to the US immediately. Fran refuses ("I'm fighting for life"), and requests a divorce, so that she will be free to expediently marry Kurt. He asks her to put off her request for a few months so she can be sure, but she is adamant that Sam leave by himself immediately:

Sam: Have things got this bad, Fran?...If things have got this bad, they've got to stop altogether. Now, I'm willing to do anything I can to make you happy. I love you. You know that. But if we're going on together, as you said to me back in Paris, I'm saying it now, if we are going on together, we've got to beat it right back home where we belong.
Fran: Is that your idea of making me happy?
Sam: I'm not taking any more chances on another Arnold Iselin. Oh, I know this friendship with Kurt is harmless enough, but you might get fascinated.
Fran: You think I might? You really think I might? Well, I love Kurt, and Kurt loves me, and I'm going to marry him. He asked me tonight...You've never known me. You've never known anything about me, not what I had on or thought or the sacrifices I've made....I'll be happy with Kurt. I'm fighting for life! You can't drag me back!
Sam: Will you get your divorce here?
Fran: Yes, I suppose so.
Sam: I wish you'd put it off for a couple of months.
Fran: Why?
Sam: I'd like you to feel sure of Kurt. That's all.
Fran: Well, it's my funeral now, isn't it?
Sam: Yes, I guess so. I'll have to get used to that idea. I guess I can.

When they part at the train station the next day, taciturn Sam is "forlorn," although comforted by Fran: "I know it's gonna be hard to realize, but you and I just can't get on together. And I do love Kurt. I stand by that. All the same, you and I have had some good times together, haven't we? I won't forget them. You remember them?...Do try not to be too dreadfully lonely, will you?" His last heartbreaking, sentimental words to her, as the train pulls away, are familiar:

Did I remember to tell you today that I adore you?

Devastated and heartbroken and ready to forget, Sam travels alone throughout Europe. He is first viewed grief-stricken at the sidewalk Cafe de la Paix - drenched and sitting by himself in the rain. Transitional elements include travel stickers on his trunk documenting his progress over three months, from Paris to London to Venice, then Rome and onto Naples (staying at the Grand Hotel), where he has already exhausted all the local sites: Pompeii, Mount Sorrento, Capri, and Brugherio. He accidentally runs into Edith Cortright mailing some packages in an American Express office. They sit down to become reacquainted, as he reminds her: "Time is something I have nothing else but." He tells her that he is now alone and without his wife, and has become semi-disconsolate: "I've sorta gotten out of the way of looking folks up." When the warm and easy-going Edith asks about his "education" regarding life, he is blunt: "I found myself learning things I didn't want to learn." She invites him to her villa for lunch, and he is joyously relieved to find some solace and have someone to talk to.

Understanding his issues and familiar with his marital woes, she senses that he is unhappy about life: "I don't want to intrude, but I'm sorry." He summarizes the reason for the split: "I guess it's a pretty ordinary story. My wife's younger than I am, and livelier." He has remained in Europe to be there for the divorce with Fran in Vienna. They use his hired car to drive, not to crumbling Greek temple ruins at Pastrum, but to the fish market to buy items for their clam chowder luncheon date. He is amazed by her $50/month rent for a beautiful villa. During lunch with the nurturing and sympathetic Edith, they discuss whether he might stay longer at Villa Cortright (Posilipo):

Edith: Could you let yourself enjoy life for awhile?
Sam: Show me how.
Edith: I wonder if you could.
Sam: Well, none of this that's happened to me was my idea.
Edith: All right. Break away from your hotel, forget about Vienna, move out here to me.
Sam: Out to you?
Edith: Yes.

Although Sam balks: "I don't see how I could...What'd your neighbors think?", he happily accepts her invitation to remain, and carry on favorite pasttimes of cooking, fishing, and repairing mechanical things.

Meanwhile, Fran meets with Kurt's stern-faced, black-garbed mother, the Baroness Von Obersdorf (Oscar-nominated Maria Ouspenskaya). As in the custom of the day, Kurt has asked her for permission to marry the soon-to-be-divorced Fran Dodsworth. The elderly thick-accented lady coldly refuses a fire for warmth or a cup of coffee. Mother-dominated, penniless Kurt, "strained" in the presence of his matriarchal figurehead, announces a delay in their nuptial plans due to the impending divorce: "My mother believes we should postpone our marriage." She corrects him: "I did not say 'postpone'." The Baroness apologizes for refusing her blessing: "I'm so sorry. I cannot give it." Fran asks why, and brashly brags that she is a woman "of considerable means" with great influence and money. With Kurt excused from the room, Fran is told in no uncertain terms by the Baroness (leaning forward) that she is too old to bear children for her young son Kurt, to carry on his name. It is a pointed rejection that realistically reflects everything Fran has been trying to suppress and avoid acknowledging:

Have you thought how little happiness there can be for the old wife of a young husband?

Crushed by the blockage of her future marriage to Kurt ("it isn't fair"), Fran manipulatively attempts to contact Sam in Naples by phone. Meanwhile after six weeks at the villa in Naples, Sam is now revitalized by his outdoor activities - rediscovering excitement in life, and expressing his long-repressed inventive spirit - to be shared with Edith! She is enlivened too: "All my life, I've been waiting for something exciting to happen." They express their smoldering desire for each other:

Sam: Edith, I've spent six short weeks with you in this house, and I can't imagine ever being without you again.
Edith: I can't imagine being without you, either. I think I must love you a great deal.
Sam: God bless you for that.

During a cinematographically-exquisite scene, Fran makes numerous attempts to put through an international phone call to Sam, to tell him that marriage plans with Kurt fell through, and to reconcile with him. As the phone rings incessantly, Edith avoids, delays and conceals answering, knowing it would be destructive, disruptive and threatening to their plans. After the maid eventually answers the phone and Sam finally speaks to Fran, she asks him to get them tickets for the sail back to America, and he dutifully acquiesces. He informs Edith that he must return to his wife: "She's dropped the divorce. She's going home on the Rex, day after tomorrow from Naples. I've got to go with her." Edith refuses to accept the jolting news:

I won't let you...I won't let you go back to her...I won't see you killed by her selfishness...I love you and she doesn't. You're content with me. You're miserable with her...A moment ago, you had the whole world in your hands. I won't let her take it away from you...You were a young man a minute ago...I've seen you shrivel the same way (with) every letter you've gotten from her...You're all wrong to go back...One word from her and you trot right back....What is this hold she has over you?

A creature of habit, Sam cannot be convinced: "Please be fair. She's in a hole. She needs me...I've got to take care of her. A man's habits get pretty strong in 20 years. It's giving you up that hurts." Edith rejects Sam's plans: "She does not need you, and you might think of me."

On the ship about to leave Naples after Fran has reunited with Sam, an unremorseful and critical Fran continues to prattle on and complain about their inadequate cabin and a cold draft, and states how she was "bored" in Vienna. She blames others for her problems - she makes disparaging remarks about Kurt's mother (an "awful, old country frump"), and then rationalizes why she is unapologetic to Sam: "I suppose I really ought to beg you to forgive me, I thought of it, but you always let bygones be bygones, and this is such a happy ending to our escapades."

She makes an additional catty comment about her own sophistication compared to the dowdy clothes of Matey Pearson (Spring Byington), the wife of Tubby back in Zenith. This is followed by another unsympathetic aside from the shrewish, wrong-doer wife, who refuses to admit she caused their rift:

As I look back, I don't blame myself, I can't really. You know, you were a good deal at fault, too.

At last coming to his senses, Sam realizes that he no longer loves his selfish and eternally-unhappy wife. He arranges for his luggage to be brought to him from the cabin, and he announces to her:

I'm not sailing with you...You and I can't make a go of things any longer...I'm not taking another chance, because I'm through, finished, and that's flat....

As he disembarks to rejoin Edith in the villa, the abandoned Fran becomes even more vitriolic:

Fran: What's gonna become of me?
Sam: I don't know. You'll have to stop getting younger some day.
Fran: Are you going back to that washed-out expatriate in Naples?
Sam: Yes, and when I marry her, I'm going back to doing things.
Fran: Do you think you'll ever get me out of your blood?
Sam: Maybe not. But love has got to stop someplace short of suicide.
(Dodsworth runs to the gangplank and jumps on just as it is lowered away from the ship. The boat whistle sounds.)
Steward: But the gentleman will miss the boat!
Fran: (drowned out by the boat's whistle) HE'S GONE ASHORE! HE'S GONE ASHORE!

Edith on her balcony sadly watches the boat sailing away from the Naples port, at a distance. She sees a figure in a small fishing boat approaching the villa. Sam stands and exuberantly waves at Edith - who waves back - they are joyous to be together again.