I had a friend who i actually met because she started dating my ex boyfriend (i think i was like 15 at the time she was the year below me so probably 14/15). She was very pretty and very down to earth and i admired her and envied her a little. There were many things over the years she did... She spent about a year trying to become my best friend, but was very secretive. We would never ever go to her house, it would always be my house. I introduced my her to another friend of mine and they started leaving me out of things. i felt like she only ever wanted to hang out with me when she had no other options, like i would ask her what she was us up to that night and she would say things like "oh i dont know yet, i'll let you know' because she was always hoping something better would come up.  She would come to me when she was upset to revalidate herself. I would give her advice when she was upset and she would literally do the opposite. She didnt want my advice, she just wanted someone to pat her on the back and tell her she did nothing wrong. She started to act weird with me and not tell me about her personal life. I asked her "what have you been up too?" and she would be like "just out with people" and i would ask "who?" and her response was "thats my personal life thanks" like she didn't even want to tell me what she had been up too.