It stinks when you don't know where you're at with a guy doesn't it! Guys so often just stop doing things they usually do or start doing new stuff and they think there's no need to explain, and we're just left wondering and worrying!
Many times it's nothing, maybe he's stressed or has stuff to do or just doesn't feel like it (we all need our own space from time to time) or has just changed his habits/routines (dunno maybe he feels that the hug goodbye feelds fake because it's such a routine now) but other times the guy just assumes you'll get the hint that he doesn't want you anymore.
I think you're best off talking to him about it, tell him what you told us, i.e. you like him and you're confused because he's stopped hugging you, and that you'd like to know whether he means anything by it.
25, female, AS with attentional dysfunction