She loves him out of pity at first, but then falls for him for real. Though he finds out why she began dating him and breaks up. In the end, they reconcile and get back together. Love triangles welcome. Maybe the FL secretly loves someone else despite dating him, but in the end she falls for the ML for real. Maybe another girl is trying to get the ML away from her because she knows. Stuff like that.

Densha Otaku | ML is a certified otaku and the FL is a very beautiful successful woman who starts going out with him thankful for saving her at one time and also because of pity

✔️ Cunning Single lady (break up for other reason but get back together) 

✔️ Because it's my first life (they  marry  to share  house but she pities him)

I’m Not a Robot. The FL doesn't start dating the ML out of pity, but she becomes close to the ML at first while pretending to be a robot partly for money and to help her ex (who invented a robot that looks like her that then broke, so she had to take its place) and partly because she feels pity for the ML and the lonely life he leads due to his allergy. Another girl does try to win over the ML. In the end the FL genuinely falls for the ML, and while he's angry with her at first when he learns the truth he forgives her and they have a happy ending