From the easy to give advice. But still, the guy cheated on the girl, you need to calm down and think it over "a cool head". Not immediately after a breakup to seek meetings with the girl, calling her to fall asleep a message, make a complaint or request to return. It will only get worse.
When the sharpest emotion will recede, the guy needs to try to understand why the girl dumped him. After all, the gap would not have happened just like that, out of the blue! Maybe he offended her without noticing. Maybe that triggered the notorious dissimilarity of characters. Or she just found themselves another partner. In the first and the second case can still be corrected, and the third better not to even try. So this girl didn't appreciate your boyfriend.
If there is no hope for the resumption of relations, it is necessary to convince yourself that it already happened, nothing to fix. Long-lasting strong feelings, mental anguish will only hurt the young man, can embitter him, to instill hostility to all the fair sex. Did he need? We need to accept what happened, accept it as an unpleasant but valuable lesson for the future.
The boy should get rid of everything that makes the memories of this girl. To remove her photos from their social network pages, phone numbers, email addresses. Gifts received from her, better to remove somewhere far away, out of sight.
Every effort should be made to avoid ex-girlfriend. You should not talk about it with friends, family. Any talk on this subject, the guy should politely but firmly to stop.
The best distraction from painful thoughts, feelings – employment. The young man should be the maximum load yourself with work, school, Hobbies. Then it simply does not have the time and desire to constantly reminisce about the former partner.
If possible, better to go somewhere away from the places where everything reminds about the girl. New experiences will also help to distract from gloomy thoughts.
Finally, no one has repealed the wise old rule of "like cures like". Still the girl did not appreciate the guy? Not a problem, the other will appreciate. The young man need only to look attentively at the fairer sex. Maybe his happiness is very close, in two steps. It is only necessary to let go of the past and start living in the present.