Like the title? And maybe where the romance isn't the main plot, or where the secondary leads at least know their place. I'd prefer something in a fantasy setting, but I guess I would have to turn towards anime then. :/

The Hospital Playlist 

A love so beautiful (Chinese drama) 

Our blues 

I feel like there are a few Japanese dramas like that: Stepmother and Daughter Blues, Tonbi, overprotected kahoko, Neechan no Koibito, Uchi no Musume wa, Kareshi ga Dekinai, Ossan's Love

Single Teacher Miss Hayako - really nice people in this one. The teachers in an elementary school have school projects and also group projects to improve their own lives. Usually it's something like physical fitness, but a project begins to work together to find suitable mates for each other. Miss Hayako is in her 30s, living with her parents, and has been content with her life. Her much younger sister is married and expecting, and her father has had a health scare, so she knows this will not continue forever. Although she goes along with this project, to some extent she is an observer going along with what she feels she should do.