ML becomes a total mess / ill / almost mad if he is separated from the FL for any reason

ML can't tolerate it if the FL leaves him or tries to leave him, or if someone tries to separate him from her. Because he loves her so much. 

Dramas like this that I have already watched:

Secret Garden (he fell ill when he was separated from her)

Our Beloved Summer (he fell ill, developed insomnia and was a total depressed mess when she left him)

Beauty and Mr Romantic (the SML here was like that)

Love Like the Galaxy (he had no will to live after she left him)

 Lou:

Ohhhhh someone watched Secret Garden! It's been ages since I've seen people talk about it. :) 

What's Wrong with Secretary Kim 
Because this is my first life

I can talk about it for hourssss. It's so toxic but I still love it so much . There is something so so magical about this drama. I have never found another drama like this. The ML is such a jerk in the beginning and even in the middle. I dropped the drama the first time I started watching it because of him. But I started it the second time because I listened to the Hyun bin's version of That Man OST. I finished it this time. I was in a kdrama slump for a long time. I still look for drama like this. ML is such a red flag, the kind of guy I would never tolerate in real life, but by the end I loved this couple, this story and ML. I rewatch it all the time. Its OST That Man is so special for me. I need to stopppp

• Moonlight Romance (in a very literal way, he depends upon her kissing him for survival)
• Flower of Evil (he falls apart when he believes she's dead, and before that when she lets him escape he goes back to her because he doesn't know what to do without her)
• Lost You Forever (SML but the love interest - he loses the will to live after he believes she's dead)

 RSB:

• My Lady General - ML basically loses his mind when FL leaves him
• Clean with Passion for Now - ML gets very upset and worried w/o the FL

I have a list, if you're interested, for couples where one party literally has a plot reason for becoming sick/distressed when the other leaves them. I note where it's the ML who needs the FL vs the other way around. 

I would be interested in that list