I believe that she is a nymphomaniac. That would imply that see is already cheating Hutch, and I believe she is. Even though she mentions in monologue (in the shower?) as if she cheated for the first time with Chris, I think she is just deluding herself. She gives signs in that sense to the basketball player, to the mechanic and to the twins that she has a hard time to control her ego and her pussy, as well as how she likes to be appreciated. If the mechanic tried to kiss her , how do you think she would react? I believe she would have embrace it and kissed him back. She was already start to "melt" as he approached her (similar to Chris). The difference is that the mechanic did not take any actions to "conquer" her. I don't think a hot woman like her is not tempted by some opportunities like this and I believe she would take (and is already taking) almost all this type of opportunities.
By being a nympho, we can explain a lot of her actions. The non-stop debauchery in the boss' house, the complete failure as trying to resist to Chris in the bathroom. She cannot control herself when it comes to sex, particularly good sex.
As for Hutch, he tried to completely conceal her from his colleagues at the office (for 6 years). I find that is not only because he is insecure, but because (i believe) he has trust issues with her. And she gave a number of reasons to deduct that she is not trustable, beginning by going to talk with Hutch's boss behind his back. I just think this is the first time he presented that she is cheating. How can someone live in a marriage for 22 years and not have notice that Vivian is not trustable? Love is not enough. I think that Hutch is also trying to delude himself from the true, but in this 22-years journey we started to create some defenses (such as not presenting her to his colleagues).
I think that Vivian has also trust issues with her husband. She doesn't believe that he could develop balls and take her, embrace her, protect her. I see this a kind of game (even unconscious) for her. How far can I go until this piece of shit mans up and conquer me back. She accepted the kiss in front of hubby and accepted to go along Chris to his bed , and Hutch did nothing.
Finally, Hutch was humiliated in the way and in the boss house by his wife (intentionally or not). He asked her not to go (ignored), he asked her to change dress (ignored), he asked her to take care with his boss (ignored). He even complained about the kiss (ignored once again). And after all of that, she went to fuck Chris at plain site. Well, I cannot believe a woman who believes that loves someone could go as far as that, unless she has a very hard issue controlling herself. Thus, I guess picturing her as a nympho could bring more sense to the history, even though I recognize that this is just a fiction.
It is just a fiction, right dev?