When I read some of these I lol'd.
If I was dumped by a girl because she wanted to date another guy, I would hate her guts, if she broke up with me because of something I did, I'd cry myself to sleep. But, it's a stepping stone for learning for the future.
This situation can come from so many scenarios so there is not really a correct answer, but if i were dumped without reason then i'd ask the girl the reason but if i were dumped because of my own stupidness then i'd probably just leave it be and try to move on in my life.
I'll think aout why, then i'll try and win her back.
I never get dumped, I simply bang the girl and then dump her myself. <3