What is interesting to me is the woman's mask. Why pretend to be a smiling woman when you are supposed to already be one. Lovely symbolism in these masks. Delicious.
So we've gone from interested to making out in shadowy corners of the room. This is escalating quickly. Their choices in masks are also interesting, with him picking that of a horned beast (foreshadowing!) and her picking that of a smiling woman (foreshadowing that she isn't happy or going to be happy with this relationship down the road?). Also they're wandering away from the party in the middle of the night. This is probably going to lead to a bedchamber somewhere.