What does he mean when he says he just wants to have fun?

he just wants sex...

it could mean lots of things;

firstly, it could mean that he actually does just want to have fun.

it's not always definate, but mostly when a guy says this it's because he does not want to worry about the element of commitment or responsibility that comes with a full on relationship.

this doesnt necessarily mean he doesn't like you, it probably just means he wants to have a "carefree" time to begin with.

However, this depends on how long you have been together. if you're feller is still saying this years on in your relationship, you should maybe sit down and talk about where you are going, because him saying this may have some founding in commitment issues.

another possibility is that he is using this as a way to get everything he wants from the relationship, without giving you anything you want in return..

HOWEVER, each and every relationship is different, and deep down you should be able to decifer which of these reasons is the reason why he says this.

if you can't work it out, maybe you don't know him as well as you think you do.