Assuming you were in this line of work at the time, I imagine your girlfreinds thought like your freind and felt threatend by it.

An expeirience I had was a freind of mine thought of himself as a bit of a psycologist, and I became very wary around him, feeling like he was trying to get in my head all the time, havn't seen him for years now.

I think one of the few ways it could really work is if you had a girlfreind that was with you on set as an assistant or something.

I can also see the pitfalls of mixing work and pleasure, it rarely, if ever works.