I have been with my gf for 6 months  and recently she's come out to me as a bisexual. Now I'm not one to care about sexuality, but what's bothering me is how has she come to this realisation in the time we've been together, I don't see anyway unless she's become attracted to someone of the same sex, how else would you know your bi?

Also now it's just uncomfortable for me to have her alone with her girl friends,  same way most people wouldnt be happy with their girl friends sleeping at a male friends house for the night, and I just don't want the stress in my life. WIBTA?
(Both 18)