"Hey, how about this? Sometimes a couple who have been arguing a lot don't want to be alone together? So they keep extra people around for as long as possible, b/c they won't "erupt" when the third parties are around?"
Quite possible, though don't you think Amy would have noticed some tension or acrimony at the salon?
I guess Amy might have noticed tension if it were there.
But...with the couples I'm thinking of, the whole idea is that the arguing, tension, silent treatment, whatever, would never break out at all, b/c they would "behave" b/c a third party was present. I'm picturing, say, Laci thinking, "If Amy's there, Scott won't start up again arguing about [fill in the blank]." Or maybe Scott would be thinking, "If Amy's there, Laci won't expect me to be as affectionate as she would want me to be if we were alone... I don't feel much affection for her lately and I don't want to have to put on."
Something along those lines. But what the heck. I'm running in circles trying to fit the facts in with my own theory. I guess the simplest explanation is that obviously, Amy would have to go home sometime!