While what everyone is saying on here is mostly true, I understand how you feel. I was never possessive, or even insecure, until I fell in love with my ex. I had been with plenty of other girls before her, and never worried about what they were doing when I wasn't around them. It was different wth her, because not only was I actually IN love with her, but we were in Online relationship. After meeting and then having to leave until I got a Visa, being away from each other was devastating. We both had abandonment issues and were insecure. So it actually worked out better for us, for a while. Problem was she trusted me more than I trusted her. But truth be told, I loved her more than she loved me. Go figure.

There isn't anything wrong with you, you just have an abandonment issue and you are in love. I learned my lesson, so fix it. Get help, or help yourself, whatever you have to do. What you have to ask yourself is this - is being paranoid and insecure worth losing the one you love? It isn't fun, I can tell you. Hold on to her for dear life, enjoy the time you have with her and live your own life away from her as she does away from you.