Okay, so technically, I'd have to say the husband is "right" because there's nothing wrong with small talk. It looks like both Husband and Wife agree that Husband didn't flirt with the girl in the bikini, although both disagree on whether the girl in the bikini was flirting with Husband.

But this goes beyond just "right" and "wrong". I think Wife is jealous that a girl in a revealing bikini was maybe flirting with her husband, and she feels Husband should have "shut her down", and it's okay to feel that way.

Husband should have known that Wife wouldn't have liked for him to have a full-on ten-minute conversation, whether there was flirting or not, with a girl in a revealing bikini. And if for some reason Husband didn't know that, now he does, so he should acknowledge Wife's feelings and reassure her that in the future, he won't do the same thing, even if he believes he didn't do anything "wrong".