Do not cry that has left you
Should not you be grateful for not being destined to fall in love with someone whose sincerity is not equal to you.
Finding a successor or feeling okay to lose it means you are able to show that he is nothing to you. Do not cry over him who left you for someone else. If he's stupid enough to take you off, you should be smart enough to forget it. Believe that in the end if he can not find a better one than you if he does not want to come back to you surely his life will not be better while still with you.