(Backstory: He broke up with me. No, I didn't cheat or anything like that. It's not that I want to get back together (we weren't compatible), but I still care about him and respect him. I still look at him like a human being. I also still feel sad about the breakup, even if it was for the best. He, on the other hand, just went cold. He seemed to just not care. He was really snappy and rude when he did it (completely unlike him). That's what hurts the most. I feel like how can someone act that way towards someone they've had history with? Isn't there just this common decency you should have even if you don't want to be with that person?)
Most Helpful Guy
To some guys, breaking up is like breaking down a creation they making for someone special. All the time and energy spent building that creation (relationship), hoping to finish that and present it to her wholly (marriage), but in the end, it didn't work out and he has to break it apart and make it again for someone else. The pieces are broken (the memories) and the thought of it or the physical reminder of it is hard to deal with and they doesn't know how to respond to it (the coldness, the snappy rude reactions).
You may understand what he's going through by being someone who cares, even if you're not in a relationship with him. He will find it awkward and he may think that you may want to get back together based on those actions, even if you have no intention to. I know guys who act like that and it's best to give them time to think about it and rebuild themselves. If they're not used to apologizing, or making ends meet, then that attitude may stick with him for a long time and they will continue to stay cold to their "bad" relationships.