Jealous/Possessive (possibly toxic) straight ML in C-Dramas

ML is completely obsessed with FL and not to a healthy degree. Their relationship is kinda toxic, but I'm here for every single bit of it! He can be kinda crazy sometimes (quite literally so), but the main leads' chemistry it's simply perfection. 

He is really obsessed and possessive of her. It's within a healthy scale, but really so satisfying! I love how he doesn't have eyes for other girls once he falls for her and how he just won't allow anyone to arm her in anyway and how he wants to keep her by his side by all means (again, it's a healthy romance, even if he is a little obsessed with her).

I guess most of us are familiar with the troupe here since it's F4 again, but for those who are new: the romance starts off in a toxic way, but ML has great character development and it's quite jealous and obsessed with FL, nothing alarming, really. If you take out the bullying in the first half of this drama, it's an overall cute and nice watch.

ML it's really obsessed with FL here, not to a healthy degree at all. He is a bit of a red flag, but then again, red is my favorite color, so he gets a pass lol

Jokes aside, he is a bit toxic, but main leads have great chemistry and the drama is quite enjoyable.

ML is quite jealous with FL, not to a toxic degree as I remember, but he is obsessed with and does everything in his power to keep her safe and protected once he falls for her.

ML it's a total yandere at first. He is really possessive and obsessed with FL, would destroy the world for her, obsessed. He does tone it down quite a bit during the second half of the drama, which (for me) it was a huge let-down, after all, I loved he's crazy. He does bring it back a little later on, but honestly, it's just not as satisfying in the end. Still a great watch tho!