Regrets (смешанная)

Based on this prompt (and tweaked it some):
Persons A and B are not together yet. A had a relationship earlier that went as far as moving in together and sharing the same bed (whether they had - or even wanted to - have sex in it is up to you). But they broke up, and A kept the double bed because it was easier/comfier/etc.
Then, A and B go out to drink one night. A gets drunk, and the last thing they remember is confessing to B that they feel very lonely after the breakup, and B helping them get back home.
In the morning, A wakes up with a major hangover and turns over in their bed. Guess who they see beside them. B, laying on top of the sheets without a care in the world.
Where do things go from there?