Haven't you watched "It's Okay, That's Love?"
This one is really mature. The script is beautiful, acting is impeccable, and the theme is really mature as it deals with mental illnesses.
I didn't like the first episode but it gets better and better and I'm about to watch the last episode now.
I normally like rom-com type of dramas but this one is just so well written and executed. Check it out, if you haven't done so already.