Why do men really cut you out of their lives after a break-up?

I agree with the guys below me. If it was a great relationship I see no reason why he would talk to you.
but guys are quite childish when they get hurt, so they decide to just leave it. That way it won't hurt them again, see it as a defense mechanism lol!
3 years is a very long time. Try again? There's no harm in it

It really depends why you broke up. If you had a great relationship but something went wrong and he knew he couldn't be with you anymore, trying to be anything less than what you were before will basically never work. But then again, if the attraction is REALLY still there then anything is possible.

It depends on the guy. Honestly it may be easier for him. I wish I could distance myself from my ex, after almost 5 years and almost proposing 3 times she decides we should break up...two weeks later she is with my best friend. We're at the same college, in the same dorm, on the same damn floor. God has a sense of humor I'm sure, but this ain't funny.

Not sure why that would happen after a good relationship. Why did the relationship even end if it was good? Also, if he was the one dumped, especially if the relationship was good, don't expect him to be happy about it.

Most women I know like to use the familiarity they have with people to get their way, so I would think men distance themselves from those women they had a relationship with so they don't feel obliged to do anything for them.

Men get really childish when they are hurt. I know that I also get a little childish when I get hurt. That would be why they cut you out. Plus, if you're not their girlfriend anymore, what purpose would it serve to talk to you and be your friend? They have plenty of other friends that don't cause them pain.

They think if they act nicer they have a bigger chance of you liking them so yeah