What does this dream mean and how can I get over him?

I'm only 15 and me and one of my first boyfriends started dating about six months ago we only dated for about a week even though we liked eachother it wasn't working. Now he has had a girlfriend for about 4 months and me and him aren't close anymore. But now he keeps appearing in my dreams and asking me out and kissing me and I don't understand what this means, why can't I get over him it wasn't like we had a long relationship I just want to move on as he clearly has.