Most Helpful Girl
Well everybody can use somebody else - you are much more likely to get used if you date a girl more educated, richer or better looking / more popular than you. This is why so many attractive guys date average looking girls - they know they will get better treatment if they date somebody who is less attractive than them.
Most Helpful Guy
If that has happened on six occasions then you can't just look to the girls for blame. You also have to look at yourself, what you might be doing wrong and certainly the kind of girls that you may be going after. You are the constant in all of those relationships. Therefore, you are the one that can change something.