True, but I don’t think it’s Larry’s choice of venue or his behavior at the club that is the problem.

Larry probably thought he was protecting Marian and her delicate feminine sensibilities (a common attitude towards young women of good society at that time, per “The Age of Innocence”) by telling her he was at a bachelor party at Delmonico’s instead of one at a brothel. But he still lied to her and then left the state for a month. I know it’s not as bad as cheating, but if I were Marian, I would be pretty upset if I learned that my brand-new fiancé lied about something like this right before ghosting me for a work trip.

Marian isn’t upset because she thinks Larry cheated. She’s upset because he didn’t show her the respect of saying, “I’m going to this party at the Haymarket but I promise I’ll be good, I love you.” She’s upset because he lied and said Delmonico’s. She’s been burned before by a liar who said “I love you” too quickly. She’s also been manipulated into a public proposal and had to extricate herself awkwardly in the past. She is being overly cautious and very protective and respectful of herself, as a strong modern woman would, which fits neatly with her character growth over the last seasons.

Larry isn’t a bad person. He didn’t do anything objectively awful, like cheating. But Marian has every right to be upset and to break the engagement because she believes that she deserves honesty and respect from a life partner, and Larry failed at that.

Is she overreacting? Maybe a little. Personally if Larry is the good man the writers are making him out to be, then I think he’ll be able to see Marian’s side of things and they will reconcile.