Wish I was straight

My best friends snogs me when she is drunk and other things happen and she tells me how fit I am and that she can't imagine her life with anyone else. It is all very passionate. This has been going on for 5 years!!! (4 times ish per year, also we live together as housemates). Then when she is sober she says she is looking for a man. When we have on occasion broached what is happening (only after alcohol), she changes between saying she is scared of a relationship with me as I'm the closest person to her and what if it goes wrong, to saying she has no attraction to me and wants a man. We are both bi. She is not out to her family. I want to move on but keep allowing her to suck me in, get my hopes up, then lets me down. We are 33/35 both female. Too old surely for all this. She has admitted that if we were opposite sex, things would be different.