Dandelion,
Sweetie, the real question is what made you so clingy? I can tell you from my personal experience - clingy behavior comes from fear. If you don't really believe you are good enough for him you will be petrified he will leave you. That fear creates insecure behaviors like clinging. If you don't believe you are good enough you will push anyone of quality away. Your low self esteem may be covered up, but only someone with self doubts becomes clingy. Work on loving yourself, flaws and all. Figure out why you are special. You are, because we all are, in unique and wonderful ways. You might need to get some help with this through therapy... spend some time and resources on yourself and when you become confident, if he is the right guy- he'll be back, if not the right one will see how terrific you are. The love of your life has to be you first, your lover second. ;)