Tbh it is kind of annoying when ppl assume it has to do with size or ability to pleasure. Too many ppl lump a threesome into a cuckhold or humiliation kink which just isn’t true. Typically, I wouldn’t even call those a threesome bc a lot of the time that’s 1 on 1 sex.

If a woman wanted a mff and she wasn’t bi I don’t think someone would assume that the women thinks her pussy isn’t good enough for her man she needs to get him a better pussy. There are various reasons why someone may be interested in threesome sex that have nothing to do with not being able to please your partner.

Personally, I think it’s like having your partner be your personal porn star. The idea of someone else being able to experience how good she is at sex is hot. Seeing her let loose and be as slutty as she wants and in an immense amount of pleasure is hot. The same way a man laying back and having two women pleasure him? How would it not be pleasurable for a woman to have two sets of hands, two dicks, etc ?

There really is a double standard with threesomes it’s a shame. I think more women /men would be open to a mfm if these double standards didn’t exist.