Hugs, not drugs! Maybe that's one of the reasons Charlie has no reservations about experimenting with any drug that crosses his path: not enough hugs.
There are lots of different types of love on display in The Perks of Being a Wallflower: the love between friends, between family members, and between a teenager and his first big crush. Feelings, and how to express them, are confusing for anyone, but Charlie has an exceptionally difficult time with it. A general lack of social interaction and a family averse to physical contact will do that to a kid. Fortunately (or perhaps un-) for Charlie, he's about to get an education he wasn't expecting in high school: a crash course in learning to love and be loved.