A lot has been mentioned about the backyard scene, but for me the bathroom scene had the most impact.
In this sequence we see here admit she is a bad wife for cheating again, but is very much into it. She wants to prolong the sex act and even chooses to gives him a blowjob (returns the favor).
This sequence hurt the most. At this stage you can tell she is nothing but a sex toy for his pleasure. "Whatever you want" - would have been a dagger straight to the heart for Hutch. and the look in her eyes as they fuck, is the look of lovers, not somebody who is doing it against their will.
here we see that although she doesn't admit it, she did enjoy it . Look how she stares at his dick. Look how she decides to eat the last bit of is cum off her face. She didn't have to do that, could have easily washed it off in the sink. In fact she didn't have to swallow if she didn't want to, could have easily spat it out in the sink. She did it by choice - she gave way to her lust and desire for Christian, and took all he had inside her.
Finally, at least she admits that Hutch would be disgusted in her and not want to kiss her.
I hope it stays that way and Hutch does refuse to kiss her (so far so good). Fingers crossed Hutch does not become the typical cuck, and this game actually delivers something different.
If it gets to point where Vivian starts kissing Christian passionately, while fucking, she might as well start signing the divorce papers.