Most Helpful Girl
Thought making such a general statement would be wrong, I think a lot of the time guys do seem to 'move on' or mourn the break-up a lot less for a few reasons.
For one, societal norms. A guy is seen crying, regardless of the reason, and now he's a coward. A pansy. Nobody wants to bring that upon themselves, so I think guys learn to internalize their feelings from a very young age
Also, if a guy is the one initiating the break-up, he's already had one foot out the door for a while. Guys tend to think over their decisions a lot in such areas, rarely as impulsive as some women can be. So while you may feel blindsided by the break-up, he's been 'moving on' for a while now, unbeknownst to you.