Are you saying that if she wore a hat and socks while he waxed her muff, that would have been somehow less weird?

I can assure you that waxing intimate areas is not at all sexy. In fact if I was to pick one way that would surely snuff out any possibility of sexual attraction it will be a genital wax. I secretly harbour a desire to kick my beautician in the head when she does it to me. If it’s not done paying somebody will trained then you can tear the skin off testicles, and cause significant bruising and and bleeding to the ‘muff’ as you put it. So perhaps make sure they’re aware of the risks. At the end of the day you should decide what your comfortable with, some people would be alright with this, some wouldn’t. Good luck OP

Walk away. This guy will cause issue in your relationship. You might already be in an open relationship, you just don't know it.

If you are uncomfortable with it, tell her rather than trying to tough it out because that will just make you resentful. If he is really her best friend then he will respect her relationship with you and they will adjust their boundaries.

If your considering breaking up over something so small you seem very determined to find a reason.

I would struggle with this. Might be better off explaining you're not the right fit and letting her find someone who has the right openness and mentality to embrace both of them.