Hidden Agenda

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

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.

Similiarities:
- Both Thai Dramas
- Both BL Dramas
- Sorn (My Stubborn) and Joke (Hidden Agenda) help the other ml with dating advice
- Both Romance Dramas
- Friends with Benefits dynamic

Diffrences:
- My Stubborn is office based
- Hidden Agends is school based
- My Stubborn starts with Sorn hating the idea of dating anyone younger, like Jun
- Hidden Agenda starts with Joke helping Zo pursue his crush, even though Joke has a secret crush on him
- My Stubborn has a noticeable age gap between the leads
- Hidden Agenda doesn't seem to have a huge age gap compared to the ml's in My Stubborn

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.

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.

similar trope of ML asking our other ML for how he can get the "girl of his dreams", only to be a guy of his dreams ? ?
in Hidden Agenda, the girl is an ex of the guy our ML seeks advice from
in Secret Lover, well, read tHe bIO pPlLlL

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.

-Thai Bl
-In both dramas one of the leads helps the other lead to chase their love interest..at first

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!