EDIT: Through the power of Google Lens, I think I got the gist of it.
>Magic disease affecting females at random. >Gives the girl regeneration (regrow whole limbs in days), pink hair, inability to feel pain, immunity to other diseases and makes them sterile. >They also all drop dead by the time they turn 20. >Some of them do the compensated dating thing because there's no "risk" involved. >Some go even wilder and let people lop off their limbs to eat because that's apparently a thing. >Main girl is sad, because she has 4 years to live and doesn't know what to do with herself. >The guy in a suit was feeding his family the amputed limbs of the main girl. Story end with his wife showing him a medical result saying either her or their daughter got hit with the immortality disease.