I just feel like I am dying

I don't understand what's going on in my life. I don't understand how I get myself to this point. When we are all convinced everything is fine, perfect, set, I freeze. Why do I retreat when things seem to be progressing so wonderfully? Is it fear the drives me away from potential happiness?
Since the disengagement I have been hopping from man to man. We hit it off, and things seem great, then I freeze up and end it. I rush to get involved, then freak out because things get serious or are attempting to be serious. I will find one little problem and exaggerate it. That gives me a reason to leave.
I'm afraid. I think everything will go down hill. I am a tragic romantic: love does exist, but it is doomed from the start (see Hamlet, Wuthering Heights, West Side Story, Gone With the Wind). I don't care how irrational it sounds. It's just easier to end things before I can get hurt. Unfortunately that hurts other people.
The last two people I've hurt, one I am currently hurting, I've felt incredibly bad for hurting. As much as it pains them, it kills me as well. Am I destined to live my life alone because I am afraid of being hurt again?
Sometimes I wish lightening would strike and everything would be clear.