There's no sense in regretting prior relationships that ended badly. What's done is done. Sure, in an ideal world, we would all see our relationships end amicably, with our exes becoming trustworthy friends. But parting on such favorable terms seldom happens. After a relationship goes down the toilet, people tend to have thoughts along the lines of: "I wasted so much time on that guy." "I knew Sue wasn't right for me. I could have been with Joan all this time." "It was a mistake to have ever even met Tim." This kind of thinking is conducive only to anger and bitterness. You won't resolve anything by trying to rationalize the reasons why things went awry.  And even checking off all the things you did right and your partner did wrong won't repair the relationship. There are some special circumstances where a person might have cause for loathing their ex and wishing they'd never crossed paths (e.g., he or she was ...