I think this part of the scene offers some good clues about what drives each of them.
https://forum.allporncomix.com/threads/justteasingu-kind-of-kindness.5314/post-230652
As far as Francis is concerned, if by “cuck” we mean a man whose wife is unfaithful to him—which implies weakness, submission, or humiliation—that is certainly not the case with him (or her).
In fact, I see them as just the opposite. A couple who have reached a point of absolute trust in one another, which speaks to a certain strength and character, especially on his part, as he is the one who gives his wife the freedom to explore her own desires as well.
I don't know many men prepared to take that kind of risk, unless they're incredibly confident in themselves and their partner. Otherwise, his reaction to the pool scene—with her letting his friend dry hump her—wouldn’t make sense.