You are in love and cannot stop thinking about the object of your affections. But a certain level of insecurity is an unwelcome part of the way you feel. You doubt that this guy will want to stay with you and you fear the misery you know you would feel should he go. However, you probably know that it is unwise to turn into a clingy, needy girlfriend. This was not the person he fell in love with; and you know that, ironically, too much insecurity might even bring about the very thing you dread. You need to manage these feelings, while doing your best to make this relationship last.
Have fun and try to relax. Do things together that make you both happy and form memories for the future. Maintain a healthy balance; spending some time with your friends and family and some with him. Go out as a couple but also go out with a group of mutual friends. Do not make the mistake of dropping your own friends, or feeling that you need to spend every moment together.
Show him love and affection, but do not continuously seek reassurance, for instance, asking whether he loves you, all the time. This can scare a guy off and make him feel trapped. Allowing yourself to get like this can spoil a relationship that may otherwise be going places. Try to maintain your dignity and self-respect. Do not tolerate disrespect because you want to hang on to this guy. He will think more of you, if he too has to try a little harder.
Be yourself. You cannot always be the perfect girlfriend. If you are insecure because of past experiences, choose a quiet moment and sit down and tell him about this. This will help him to understand you and will establish a pattern of honesty between you.
Respect his independence. Men value being about to do their own thing, even in relationships. Give him time to hang out with his friends or just himself. He will be more likely to do the same for you in return. By doing this, you create a standard in your relationship that is built on respect and autonomy. Relationships that are made of two independent people tend to be healthy because the parties involved don't have to be attached at the hip. Your guy will appreciate being able to do things he loves, with or without you.