If you broke a young man, at the time of the breakup don't talk about the reasons and your motives. Particularly, if the faults of the beloved. Most likely, subconsciously, you both understand the reasons, even if you don't want to admit it. Just tear off the connection.
Some time you both need to spend in solitude and do not think about each other. Even if one of you find a new love, the other in the best case, should be happy. Or, at least, not jealous not envy.
Distract yourself on something nice that will give at least the illusion of happiness. You realize that life goes on, no it didn't ruin anyone, and no one is innocent.
After the break, which can last from months to several years, meet again. Tell each other about the achievements in professional and personal spheres. I sincerely rejoice for each other.