Hidden Agenda (2023)

Star in My Mind is Part 1 of the Star and Sky series.
Dunk and Joong play the main characters.
This is similarly set in a university/school setting.
If you enjoy their on-screen chemistry/acting, this may also interest you.

Both of these Thai BLs center around a male lead who, in the wholehearted pursuit of a girl he has a crush on, falls for the man who helped him along the way.

Main Protagonist is under the misconception that the other lead is their love rival.
Happens in university/school setting.

ML is playing guitar and is singing
MC asks for favor and it includes flirting in both cases
The opposite is while Tine wants help from Sarawat to get rid of Green, Zo wants help from Joke to hit on his ex
In both ML falls first and is stuck in one sided love
In both, MC is pretty dense
They have funny friends with silly ideas that makes them approach their male leads

Both dramas have one main lead secretly in love with the other. Because of his secret love, he starts doing something he wouldnt really want to do under normal circumstances to help the other lead (MSP - ml becomes school president; HA - ml becomes oth ml dating advisor).

Both dramas are mostly fluffy school/university feel good dramas with handsome leads.

Differences: MSP is actually good and has a solid story while HA doesn't have any sane scriptwriter in the crew.

same sort of story, about a guy that can see ghosts and helps ghosts resolve their problems

Sky In Your Heart is Part 2 of the Star and Sky series so be wary of that going in.
Otherwise, Joong and Dunk are also in this series (albeit as the B couple).
If you enjoy their on-screen chemistry/acting, I'm sure this may also interest you.

Nice male lead? check! Self-discovery and first love? check! Musically inclined male lead who can sing? check! Non-toxic, sweet, light and fluffy, feel-good story to warm your heart? check!check!check!