As much as I'd hate to admit it I have emotionally withdrawn from 2 relationships prior to breaking up.
The first one he and I could not get along. The relationship really had no future but he didn't want to let it go. He is pretty crazy about me but our personalities just didn't go together. I didn't want to break up with him b/c I knew he loved me. So I just started doing shyt so he wouldn't want to be with me ie pretend to get mad at shyt that I wasn't mad about or just start arguments for no reason. He eventually had enough and broke up with me. I played the roll so well. I even cried and told him I was so sorry. Then he wanted to get back together a week later and I was like "No I think it's for the best." He was so confused. This was like 7 or 8 years ago and I just saw him 8 months ago and he told me that he will always love me and I broke his heart.

It sucks b/c I did all that so that he would feel okay about the break up. Damned it you do. Damned if you don't.
With the second guy, we just had fundamental lifestyle differences. Hanging out was cool for awhile but all he ever wanted to do was sit on the sofa and watch basketball. He never wanted to try anything new. I do remember just sitting on the couch with him one day. I looked at the TV, looked at him, looked at the TV and then looked at him and thought "if I stay with this dude this is all my life will ever be; sitting on the coach watching TV. " I don't even like TV. At that point, I began to check out. But not too long after that I found out he was cheating. I was hurt but also kind of relieved b/c I had an out. He cried and said he would never do it again blah blah. I told him we could be friends b/c honestly I wasn't completely checked out yet. Over the course of a few months we decided to "work on our relationship" in reality I was just getting him out of my system. Then the day came when I was ready to let him go and I told him that I wasn't interested in friendship or anything else. He literally broke down and cried and told me he thought we were getting back together and he had been working hard to make things right but I had no sympathy in my heart for him.

I didn't talk to him for a year or 2 after that day until he hit me with an email saying he missed me blah blah blah. I didn't even respond.

Damn I was cold.
Going forward I would handle both situations differently.