Try My Girl (2005). It's an older drama, so a bit more conservative (and maybe slow paced) in comparison with today's dramas, but I really enjoyed it (ignore the fashion style;)). I actually just finished watching Marriage, Not Dating and thinking of rewatching My Girl because of it.
I won't say too much since I don't want to spoil it for you, but give it a few episodes before deciding whether to continue or not. For me, it really picked up after episode 3.
There is also a Thai remake (2018), but I haven't seen this one yet, so I can't say whether it's as good or not.