Have you ever had a friend who was just "there"? Like for the fun of it? Leading you on?

So technically ever since 3rd grade, we were friends- well “friends” so, why lead me on and tell me that your there for me just to leave me and go with people that literally want to break me down and say that I won’t make it anywhere? (This is a past question- but I need this answered so it doesn’t happen again if you know what I mean.)