1. It's torture. You're hanging out "as friends." Then they do something that makes you smile. You suddenly want to kiss them but can't.
2. False hope. Admit it, it's there. And if it's not there for you, it probably is for your ex.
3. You can't undo the past. Everything from the past happened. It's done. The good and the bad.
4. You can't talk about your personal lives. It's awkward.
5. It's awkward for your mutual friends. They know you dated. They remember all the bad things more than the good things that happened when you were together.
6. The odds of finding true love are slim if you're still hanging around your ex. What new guy/gal wants to hang out with your ex every weekend?