Well, if the partner isn't against it, then there's really no issue.
Now, if this is not the case, then they should break up because it's her job and her life, so she should make her own decisions regarding that(I would ask her to be safe during sex and to both of us do some blood exams tests from time to time, though).
Now, I think the main character has some kind of fetish with this situation. Nothing is wrong with that, it's just funny in a way.