The backyard scene was way before kitchen and toilet event, so we couldn't see or know anything before about the backyard event and until now we are just assuming what could have happened there.
For me like
TonyMurray already mentioned it's quite possible that Vivian took the initiative at the dinner after saying in silent "I love you" to Hutch where he was given the task to write a list by Christian and ordered to stay where he is.
Christian could have asked Vivian if she needs a drink, she denied and asked Christian if they could have a talk in private.