I think that's a mental thing. You're young and in love, and you're going to think about him often, that is just what happens. Scent, as you know, is closely tied to memory so smelling cigarettes might trigger you to think of him, but I don't believe that you got yourself addicted to nicotine from secondhand smoke or kissing him.

PS: Stay focused on school and yourself, you're young and so is this relationship.