As a crusty old geezer (26), until you're at least 24 your relationships should be about having someone close that shares similar interests or at least does fun activities with you. Go see the world, make soda bombs, whatever. With the exceptional handful of cases, going for something that will last forever is too much. Your interests will change, what you value will change, financial situations will influence how you live, etc.
So yeah, getting hurt sucks. But don't let that discourage you and don't go into a new relationship expecting 50 years of marriage and 2.35 kids. Just go have fun as long as you can Thats where you'll grow the most. And hey, if it doesn't end, BONUS!