People change. Especially at your age - you were kids when you picked each other out, so finding out you're actually not a good match now is rough but also not very surprising. With that said, sometimes people (especially young people) say things they don't genuinely mean when they're very emotional, so I do have a "use your words" recommendation before you fall too far into the pit of despair:

If these changes are recent, it's probably important that you figure out where this is coming from for your own sake. It might hurt more but it might also turn out to be something solvable. You need to sit down with him and, while staying as composed and neutral as you can, discuss where things are and where you both see them going. If he's fine, this is over and it's time to let it go. If he says he's still in this with you, share that you're feeling like he's pulling away and ask where it's coming from. Share how hurt you were by what he said and find out why he said it - no one ever says things like that without there being some hint of something genuine behind it. Be as vulnerable, calm, curious, and accepting as you can be, and do whatever you can to not be defensive, and it should help him feel like he can open up better than anything else is going to. Discuss solutions or paths to solutions for anything that does come up. I will warn you that it's an incredibly hard thing to do and you never know what's going to come out of it - you could come out with both of you having personal growth goals and maybe some new communication strategies and you could be stronger than ever or you could find out that something has happened to end this relationship for good that colors your view of way more of the relationship than you're expecting or anywhere in between.

Best of luck - I hope you end up where you need to be in the end.