What type of shoot was this for? I have a few friends who were models and if there was anything like that the photographers knew how to take the pictures to simulate them in illicit positions without them actually HAVING to do it. Unless it was for a porn magazine where its close ups I fail to see why she actually was required to have sex with the guy. :S I'm not judging her by any means, but I do feel she was taken advantage of.

As for anyone in a relationship with someone who's doing that it all has to be in your comfort level I suppose. If you know that stuff like this is happening and is a part of her career then you have to evaluate if you trust them enough to not cheat on you. If you trust her and trust yourself (by "you" I'm generalizing) then it shouldn't be an issue at all.

Hopefully as well that's not all her photoshoots entail. Not every shoot is going to require a person to physically have sex.