I want dramas where the female lead is in a love triangle with the male lead and another guy who happens to be her ex-boyfriend. She likes the male lead and ends up with him. The ex causes problems for them.

Have you seen Personal Preference casting Lee Min Ho? It's somewhat similar. 


http://mydramalist.com/19-personal-taste

Weightlifting Fairy Kim Bok Joo includes a little of the male's ex trying to get in the way but ends up with the female lead. http://mydramalist.com/19262-weightlifting-fairy-kim-bok-joo

The only other drama that fits your requirements (and that I've seen) is Personal Taste ^ as stated above my reply.
It's okay , that's love 
Thanks for the suggestions everyone. Please post more if you have them.