I could go into a lot of detail, but I just don't feel it's necessary. Not when this one point kind of sums everything up: who, in god's name, would say something like, "You betrayed me!" in real life?
If someone said this directly to me, as in the context of this movie (i.e., supposed sexual betrayal), or really any context, I would laugh. Because no matter how dramatic my life has gotten (Ooh, I'm starting to get older and I have a teenager and pre-teen via my marriage to someone with kids, so I should probably cheat on my spouse with someone younger and more passionate than me in a sad, sad attempt to recapture my 20s, and when, in a shocking turn of events, that same temptress isn't that serious about me and doesn't even attempt to understand how serious this is for me, I will throw a tantrum that shows, not only am I selfish and deluded, I'm also not really mature enough to have kids, let alone sex), I refuse to be around people who talk like this. People who speak in a way that makes it seem as if their life is so important and serious that it requires dramatic words like betrayal. Unless you're accidentally sleeping with your mother, and thus are betrayed by fate, or have found yourself in some Shakespearean coup to take over your kingdom, please don't talk about betrayal. Let's just assume the audience can figure something like that out implicitly through the characters' actions.
Good sex scene though.