What makes a guy jealous?

[MissCurious1]

I was going out with this guy for almost a year now..We were best friends in high school and we love each other..But for some odd reason, he doesnt wanna be with me anymore. He's neber been with anyone else except for me..So he told me his reason is because he wants to experience relationships with other girls. And also, he thinks I was too dependent on him..But anyways, I think he's just scared to be committed. But the thing is, hes such a sweet guy and I love him so much, I don't want to lose him but i don't want to let him feel free to come back to me whenever he wants because he will realize that we had something good and he will regret. But what should I do to make him realize this? I don't want to run after him, just make him realize that he we were and still aer worth it!