Anyone know what this Asian drama was called?

I watched part of a drama years ago and would like to find it. I want to say it was named "Younger Man" or something like that, but nothing is coming up through searches, so I could be wrong.

I'm also hazy on the details.

The show was about a woman--maybe in her 30's?--who was interested in a younger man she'd see at the gym. The man, however, unknowingly fell for the girl's mother, so the girl started dating her younger brother's best friend.

I honestly don't remember any more than that. Anyone recognize this?