How much often girls that make out end doing something more than just making out?

Anonymous
I am really sad and disappointed asking this question, but I have no courage to ask directly to the interested girl. I know that is pretty unusual, but, between my female friends, the majority is not straight: they are 6 bisexual, 5 lesbians and 4 heterosexuals. I’m in love for one of my friends from more than a year, and I know her from almost three years. I made nothing because she was in a relationship (pretty important, two years). It ended last week, he left her last Sunday and she was really upset. Saturday night me and many of my friends, including her, were invited to a birthday. She drank a lot, thing that she never does, but she didn’t looked drunk. Around midnight I found her outside in the garden kissing with another of my female friends. They were kissing gently and they caressed each other’s body. I’m feeling really broken for that, it’s not even the first time: before her, we are talking about 4/5 years ago I was really interested into a girl, I told about my feelings in October and she said to me something like “I’m sorry, but this summer I’ve understood that I’m totally into girls”.
The girl that I’m in love with always said strongly to be totally straight, I’m less close with the other one but she always said to be straight as well (and I know she had in this years many short story with different guys or one night stands); but in the end last night I found them kissing each other. I don’t know why so many girls are into lesbian action, but I’m asking how much often after making out girls end in bed together? How easily it goes more far than kissing? Most of all, I am asking if she has made something with her and if I have to start thinking that she could “turn” as well into a lesbian/bisexual. How much is possible that they are a couple now? Should I try to talk with her about my feelings and making a step even after what I’ve seen? Do you think it would be rude to ask about what I’ve seen? (They haven’t noticed that I’ve seen them)
How much often girls that make out end doing something more than just making out?
2 Opinion