Rhapsody. My only advice is to take your time getting to know people you're becoming involved with and if they seem selfish, get out. This is to say, they (usually) wont change so don't waste your time if you suspect a bad egg.

Someone stated earlier that people present their best faces when dating and that's true so unfortunately it can be hard to tell who's a selfish bastard and who isn't so again, don't get attached too fast.

Also, if recent relationships have made you feel this angry and bitter, a break is probably in order.

Good luck.

Cyran0