It's interesting to look back at Irwin Shaw's story from the perspective of our own time. Michael's confession that he likes looking at other women and is occasionally aroused by them isn't exactly extraordinary. Perhaps today a couple would merely laugh off the whole issue. Or conversely, Michael's attitude might today seem much more primitive and unacceptable than it was sixty years ago. Much of Shaw's fiction, however, was pathbreaking in its time. He writes with a straightforward frankness about sexual issues everyone is aware of but perhaps still, even more than half a century later, rarely talks about.
Yet one wonders why it's necessary for Michael to make this confession. Most women are doubtless realistic enough to know that even if their husband or boyfriend loves them, it's unlikely that he's blind to the attractiveness of other women. Though in the 1950s and early 1960s, people didn't generally talk about this fact, it's hard to believe that even then it was unknown or unrecognized. So the story needs to be understood in the context of a time when literature was opening up and dealing with the final jettisoning of the old taboos about what was acceptable to deal with in writing. Still, the fact that Michael needs to be so "honest" about his feelings indicates that perhaps his constant ogling of women is a problem and not just the harmless and ordinary thing the narrative suggests. (As an aside, it's worth noting here that "The Girls in their Summer Dresses" was reputed to have been President Kennedy's favorite short-story.)
Shaw might have given the story more insight into human nature if Michael had turned the question back upon Frances and gently asked if she does the same thing and similarly can't help looking at other men. Instead he merely says that "some women are like that" and knows Frances isn't one of them. In this point, and in its general tone, the story inevitably conveys the usual gender double standard, but it does so behind a facade of progressiveness. Nevertheless, it's a poignant vignette about human frailty.