I am confused, is this girl having an intimate relationship with a gay friend?

[Alex A]

I like this female coworker and I know she has a best friend that is gay. I am worried because first I don't know if she is straight or just likes guys who are into guys. I know that my mother has gay guy friends but not as best friends, just friends. In this coworker case, I know she supports gay marriage and is into "girls who like boys who like boys". Should I rest assure that she is straight, or should I move on and believe that is actually having an intimate relationship with her gay guy friend? Im worried please help