Relationship Woes and Advice 22: In Which Two Problems Prevent Each Others' Solution

[The Succubus]

I would class it as the following:

Crushing - "Gosh, he/she is really, really gorgeous. I'd definitely be interested in a little NSA HFT with them..."

Infatuation - Wistful sighing and daydreaming about that person. A lot of your thought processes revolve around that person.

Love - Both of the above, together with being highly aware of how that person makes you feel good about being you.

EDIT: I think I can boil it down further than that:

Crushing is physical attraction. Infatuation is mental attraction. Love is the emotional bond that results from the combination of the two above. The three can be mixed in various amounts.