Are there any romances where the main character has an awful personality but their love in...

Red mansion
https://www.mangago.zone/read-manga/red_mansion/

Sand castle
https://www.mangago.zone/read-manga/sand_castle/

Checkmate(TAN)
https://www.mangago.zone/read-manga/checkmate_1/

Black Mirror.
https://www.mangago.zone/read-manga/black_mirror/
Kinda if I remember well they strangle each other in bed

.The Pawn's Revenge.
https://www.mangago.zone/read-manga/the_world_of_pieces/

Secret Relationship.
https://www.mangago.zone/read-manga/secret_relationship/

After Killing You
https://www.mangago.zone/read-manga/after_killing_you/

https://www.mangago.zone/read-manga/hardcore_bl_anthology_the_tosa_s_master/