lighthearted warm cute romances

I'm gonna suggest something unknown but I watched it today so it's the first thing that came to my mind:

Senior Secret Love: Bake Me Love

It's a lakorn but nothing like the usual (I don't like lakorns tbh)

I am guessing you are looking for a Chinese drama since you posted in the Chinese forum. :p I haven't seen many yet, but I can recommend:

Boss and Me
Say That You Love Me

Tbh it's really hard to find Chinese dramas that are lighthearted. But I'll try my best.
You're already watching Love O2O and Boss and Me, so I recommend:
My Sunshine - It's based on a novel from the same author of Love O2O and Boss and Me.
Master Devil Do Not Kiss Me 1 and 2
My Amazing Boyfriend
Hello Mr. Right
Fool in Love with You - It's being subbed yet though.
I Love My President Though He's A Psycho

There's also Operation Love that it's going to air this month, but I don't know when subs are going to be available.

Boss & Me
Love 020