Obviously every time she has sex with Christian, she will say it is absolutely the last time. Then she'll have sex with him again and tell him it's the last time. And so on, and so on, until something actually breaks – which might be Hutch, might be Vivian, or might be Christian.
I'm still not sold on Christian getting Vivian to fuck other people, I don't think that's something that works for him. But he's certainly opened the door, and Vivian might fuck others as a result of her new awakening, and Hutch's words at the end of the first update.