Any romance dramas or movies where the male lead is the ex-boyfriend that comes back into the female lead's life and still loves her?

Discovery of Romance 

I have a lover- (ex husband)

My love Eundong 

Actually fits your criteria:

Not exactly what you've asked for, but in these dramas the leads became close and each fell in love (but didn't necessarily date) before they were forced by circumstance to separate (not a situation where one or both of them decide to break-up). When they meet again, the ML either still has feelings for the FL or falls for her all over again: 

The ML thinks the FL betrayed him and tries to hate her for it, but he can't completely shake his feelings for her:

 AH :

Actually fits your criteria:

Not exactly what you've asked for, but in these dramas the leads became close and each fell in love (but didn't necessarily date) before they were forced by circumstance to separate (not a situation where one or both of them decide to break-up). When they meet again, the ML either still has feelings for the FL or falls for her all over again: 

The ML thinks the FL betrayed him and tries to hate her for it, but he can't completely shake his feelings for her:

Thankyou AH! ^^