Drama where some regrets breaking up with the lead?

Like in Personal Taste, one of the guy regrets leaving the main female lead.

Love story in harvard -- The main female lead regret leaving the male lead without saying goodbye.

Me too, flower -- The male lead broke up with the female lead and in the end, regretted it.

King2Hearts -- Same in Me too, flower. :)

Goong -- The supporting female lead left the male lead and chose to pursue her dreams but then, regretted it.

My girl -- Same in Goong.

Buzzer Beat -- The male lead been cheated by the supporting female lead, but in the end, as usual, she regretted it. :P

Try Ohlala Spouses (http://mydramalist.com/korean-drama/5412/oohlala-spouses). They're actually a married couple and he's horrible to her for the whole first half of the drama, then he ends up regretting it and wanting her back - especially when an ex of hers shows up (another case of regret?)

i think both "i need romance" drama series have that concept. Especially the first one.

I Need Romance- Male lead left the female lead, regretted it, and tries to get her back. Unfortunately for him, a new man appears in her life A Gentleman's Dignity Innocent Man- Woman leaves male lead and regrets it Protect the Boss- Supporting female actress left the male lead for the supporting male actor and regretted it. The supporting female then left the supporting male actor for the main male actor and regretted it.

My Prince is a Chinese drama where this occurs a lot. I think at one point it occurs for every brother and the mother lol. But I thought it was a pretty good drama as a whole.