Most Helpful Girl
It may be because girls get it out of their system earlier in the breakup, while guys (from my understanding) keep it in and don't process it as quickly. In my last breakup, I had my mopey phase, and then I talked it out with people closest to me, got that whole support group base going, and then was able to move forward with more ease AND benefit to myself. I've seen male friends, however, try to cover up the initial shock (no matter who instigated the break up) by closing up, not talking about it with their friends to a *great* extent, and maybe "distracting" themselves with other relationships, partying, etc. I imagine that probably makes the lows that follow the highs so much heavier for dudes and thus harder to process in the long (er) run.
Most Helpful Guy
I think because guys tend to keep everything in while women will be more open, which will help with the healing process.