Same here. For all that anyone might have to say about Hutch being weak or not dominant enough (etc.), I think what he got right is that this started with Vivian, and if it's going to stop, it ultimately will have to end with Vivian. Sure, Hutch could have reacted differently, angrily, and said it was all over, or even had an extreme violent reaction, but he picked up on his wife becoming motivated to do it more than just to save them from dire financial circumstances. That was the initial reason she was motivated to act, but she came to enjoy the experience more than she was willing to admit to him and to herself.
At first, Vivian made the stupid move of going to speak with his boss in the morning, thinking she was going to handle the situation. Instead he set forth a strategy of divide and conquer, pitting husband against wife. He told Hutch to leave his wife at home after he had told her she better be there and sent her a dress to wear for the occasion. This sowed conflict between them, and when she showed up having "won the battle" and was still of a mind that she had to handle the situation (while having experienced more of an initial attraction to his boss that she was willing to admit), she played right into his trap.
On the drive to his home, Hutch repeatedly tried to warn her (as he had the previous evening when she suggested the idea) about the kind of man Christian is (a charismatic womanizer), to which Vivian responded:
"I'm fully capable of handling myself if he says or does something inappropriate, okay?"
"I'm a big girl. Let me worry about me."
Then after she agreed to sleep with his boss, Vivian told Christian while they were talking in the kitchen:
"My normal self doesn't exist anymore...my normal self would never have slept with you."
Then when her and Hutch were having the talk at home, Vivian further said:
"These last few days I've felt like a ghost living outside my own body...seeing everything that was happening but unable to do anything about it."
And during that same talk at home, Hutch told her:
"Like you said, you're a big girl. I'll let you worry about you." (echoing her own words from right before she gave in)
"Do it...don't do it. It's up to you." (either she has the willpower/self-control to not do it or she altogether wants to do it)
So yes, I would like to see more of Vivian's willpower/self-control come to the forefront at some point, hopefully not too late for any hope of salvaging her marriage or herself, perhaps as she thinks more of consequences and what she's sacrificing. Is it worth becoming less and less recognizable in relation to the person she was or ideally wanted to be (her ideal self)? And even if her actions save her husband's job or family financial security, will she in effect stain her reputation and become so different compared to who she was that she can no longer be the wife she was or the woman her husband loves?
Those are some thoughts I've had about this. Maybe they will matter in the end; maybe they won't. I'm still hoping we're not going to see a total fall from grace for Vivian and utter despair for Hutch while Christian gets everything he wants and just continues to move forward, gleefully victimizing couples during a time of weakness and feeding his ego while doing it.