Films with unusual/dark romance?

Hello! I watched the ravine of goodbye a few days back and the relationship between the ML & FL was SO interesting, i would love to see more dark/unhealthy relationships depicted like this. The reason i'm asking for film recs is because i'm in a drama slump right now but if you feel like that drama is fitting to what i'm requesting feel free to rec that as well

Some other examples : 

Liar x liar (step siblings)

Himizu (just plain unhealthy)

Off the top of my head:

• Vengeance Can Wait (I don't even know if you can call it a "romance"--maybe?)
• Addicted
• Lust, Caution (very explicit; proceed with caution--check out the tags if you do decide to watch it)
• Black Coal, Thin Ice

Somebody - he is actually a psychopath? She is suffering from a light autism and both end up in their strange relationship where one is in love with the other while the other loves but also wants to kill them.
Lies Hidden in my garden - this would be a huge spoiler to reveal but this relationships Is so not what it appears to be at first
Kidnapping Game - this drama has one of the most realistic romance scenes you will come across in drama-land. Absolutely beautiful but their romance is quite toxic since they are playing a kidnapping game, with more twists than at first assumed.


Then there are of course a ton of Thai dramas that are all toxic like Kleun Cheewit, My Forever Sunshine, Praomook, My Husband in Law