Severus smiled at Lily as he tried to cheer her up by doing his best to dance, make it seem like they were at a ball of some kind. Maybe one day... but he stopped that way of thinking the moment the idea crept into his mind. He would have to enjoy what he had when he had it because the future did not look good for him.
When the song stopped Severus stopped moving, he didn't let go of her yet. "Do you want something to drink?" He was acting so against what, most people saw as his nature that even he noticed it. He was being social, he was dancing, he never was social and dancing was something he had never even considered until Lily mentioned it.
He knew that getting a drink would mean he would have to let go of Lily but maybe that was not such a bad thing, her closeness was having an embarrassing effect on his body. And the urge to just kiss her was still there too. Life was so complicated at times.