Focus on the story and not the sex

A doctor working with medical interns notices how one of them falls ill with a weird disease. After the intern assaults him, biting his neck because he has become a newborn vampire and is blood-starved, the doctor diagnoses him with “a rare blood disease, cause unknown” and puts him on a permanent transfusion list.
They live together for 37 years, a couple trying to live and lowkey love one another while the apparent age gap between them only keeps increasing.