Why My best friend F20 wants all the guys? Me:F19

I love her personality, and we get along.I am an only child and she has been a sister to me. However, whenever we go out she always wants boys attention, and afterwards acts like she didnt want in in the first place. Normally that wouldn't annoy me, but recently I liked a guy and kept it to myself, because why would i tell her it was new. Yesterday, after learning he is rich, she started flirting with him, IN a second she told me: ahhh he is just my type. I mean, i get it. Its okay, she does not know I like him. But i get annoyed when she flirts with EVERY GUY in the room. It is not just that, even she changes her personality and acts like a pick me. I feel bad, and I know i am pretty and fun tl talk but sometimes i feel tired, because i wanna be loved yk. why is it so hard to find a guy that is on the same page. I am starting to lose hope!