Most Helpful Guy
Everything you described is explained by someone being extremely self-centered.
After you break up why would you still want to be friends with her? He wants to keep you available so he can try to reignite things in case nothing else becomes available.
When she starts seeing other guys, you get mad but then allow the favour of meeting other girls upon yourself. See above.
When she starts ignoring you, you don't like it. It's all about him.
When she says sorry for her mistakes and arguments, in return you don't apologize for your part. When you are this self-centered, you didn't do anything wrong and it is all her fault, so why apologize?
Lastly, when she decided to move on, you get mad at her. He doesn't want to lose his contingency plan.
So, what's ur purpose? To keep everything in place for his comfort and convenience.