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.
Questions About Love
Is Charlie in love with Sam or just infatuated with her? How can you tell?
Why does Sam love Charlie? How would you describe her feelings toward him?
How do different characters show their love differently?
Why does Charlie count how many times people say "I love you" or hug him? What's that all about?
Chew on This
The only way Charlie knows how to show love is by buying presents.
Charlie wants to know what love is, and he wants Sam to show him.