Hi yuka
Well it sounds like you have very strong attraction astrologically to this guy. I can see why he would attract you and the compulsion he may provoke in you, depending on how strong the orb is.
But tell me if you use your logical head not your emotional head, would this guy be "suitable" to date your best friend? Is he good enough for her? Sorry to ask that but he sounds like part of the atraction is that this guy has an element of "bad news" about him. Think about that.
Now the hot and cold thing may be because he is treating you mean to keep you keen Or he is affraid to be emotionally vulnerable.
Not sure if that helps or just clouds issues for you, but the astrology does sound compulsive. 
Lov n hugs
Lis