My friends want to start a DnD group, and one of them wants to be a necromancer skeleton

I am a new DM and one of my players, my boyfriend, wants to be a necromancer skeleton that basically can’t die, sort of like Voldemort with the horcrux.

We are starting off at level 1.

Is it at all possible to do and if so how would you do it?

I’m trying to be extremely careful not to make him overpowered as I have played sessions with couples and the PC always gets overpowered and it drives me nuts