a couple of reasons. i know there are performers both male and female who dont care, but i would guess that the majority would rather not have the significant others there.

1. i would say half of the guys who accompany their girls to set arent there to make sure the girl is okay, they are there to be a voyeur and watch her get fucked like at a swing party. sorry, this is work, not a party.

2. i myself would never want to watch my other half getting the shit banged out of her with me watching flaccidly from the sideline, so when some other dude seems content with doing that, it bugs me.

3. as for females accompanying their male performers to set, i would assume that females wouldnt like it, because it potentially leads to the girlfriend (esp. if she is in the business) getting catty. "you looked like you liked it too much, you kissed her for too long", etc. etc. i think it makes the female uncomfortable.

4. no one out there brings their other halves into the office on a wednesday afternoon to watch them type memos and sit in on presentations. so why is it acceptable for them to watch us work? whats the difference?

once again, these are just random thoughts and it no way should be construed as factual for every performer. its just how i see it most of the time.