I want drama with evil 2nd female lead who is successful in causing problems between the couple...the ml is foolish to belive sfl rather than innocent fl and thus he regrets

He grovels or repents for his mistakes

A good character development of ml

It sounds like some otome game (FL - falsely accused villain, SFL - evil saint heroine, ML - prince who was engaged to FL, but betrays her...). Okay, I don't know any drama like that (only anime or manga).

From drama world: requirements are partially met in cdrama My GF is an Alien, it has yandere SFL and ML believes her. ML has good development. That is all. FL has other goal than love, so she doesn't care much what evil characters are doing.ML has some memory problems, so he doesn't grovel.