u/AdDangerous9852

I think I am developing more interest in the idea of having a threesome and my girlfriend has expressed some mild cautious interest in the recent past as well.

The problem is, neither of us really wants someone of the same sex to be involved (which I hear is somewhat typical). She is also bisexual, but is not overly comfortable with the idea of having any sexual interaction with another female.

How do I go about approaching this subject with her?