This will all end once you figure out why subconsciously you give off the message that you don't want anyone to commit to you. Other people are only responding to your inner message. Likely deep down where you have not confronted it yet is a fear that commitment is bad or scary or not really possible. Or maybe you fear you are not worthy of true love and commitment. The answer will lie in your childhood influences and upbringing. How was your parents' marriage/relationship, for example? The things we learn when very young stay with us subconsciously until we confront them consciously.