I recently saw an ex-date. He didn't acknowledge me, but I still think he's a fine person and will make a good husband. I said this to my friend, and she was a bit surprised that I could speak positively about somebody who hurt me. So, that reaction is what triggered this post. Do we allow our emotions to control us?
Don't speak lashon hara about someone you've dated just because he hurt your ego. If he is, otherwise, a solid person who will make a good husband for somebody else -- then don't get in the way of the shidduch.
This seems like common sense, and like, DUH sefardi gal. But the thing is: it's not. Even in dating, one has the obligation of the beautiful mitzvah "v'ahavta l'reeacha kamocha." Don't let grudges and bitterness get in the way of someone else's opportunity for happiness and greatness.
Also, treat people you previously dated with respect -- don't bad mouthe them, don't ignore them and treat them as if they don't exist, don't bash their looks by saying how unattractive they are.
The key is to take yourself out of the picture and view every Jew as an individual who has similar goals as you do. You're not the only one who is struggling with shidduchim and hoping to get married. They are the future parents of your childrens' classmates/generation.
Daven for your ex-dates, try to suggest people for them, etc.