She's in love with both the male lead and the 2nd guy. She's conflicted because of it. She eventually chooses the 2nd guy first, but then realizes in the end she wants to be with the male lead and they get together.

Jealousy Incarnate - This fits what you're looking for.  However, I don't know how it ends (who she ends up with) as I put it on hold after episode 15.

protect the boss
Dream high
maybe also you like it has also a movie
kurosaki-kun no linari ni nante naranai
MARRIAGE NOT DATING
From 5 to 9 - Jdrama

@Neyjour - Was actually thinking about watching that next.

@Safae - Will check them out.

@yusuf7016 - Seen it.

@Meg - Will check it out.