Most Helpful Guy
It's a coping mechanism. Whenever I go through a break up, my brain just switches off, emotionally.
I will still care about a girl, even love her, after a break up, but since we're no longer a couple, I can't act upon those feelings.
The emotional dichotomy flips a switch in my head that shuts down those expressive tendencies. Sort of like an emotional circuit breaker, in that it protects me from overload.
I'm not saying it's the best/healthiest method, but it's also an automatic reaction. I don't do it consciously, and I suspect that other men don't either.