IIN for a guy to want his girlfriend to shave her head?

Sounds like the typical defeminization process of a narcissist. They do it to strip their partner of their confidence and womanhood, and to make you less attractive to other men. Now I wouldn't say that simply having a thing for bald heads is a bad sign, but wanting to do it in your sleep for example, now that's a red flag. That would be doing it against your will which is a power-move for a narc and makes him feel in control. They get off on control. Just keep your eyes open for other red flags.