High school Sweetheart Statistics!?

Okay. So me and my boyfriend have been together for about 4 years. We're about to be seniors in high school and very in love. I cannot imagine my life without him. Whenever we have broken up we get back together cause honestly, we can never get over each other. I love him to death and for me, this isn't a high school thing. I don't want just high school with him. I want everything with him-a future, a family, etc. And I know I sound like a silly in love 18 year old. But it always felt different with me and him just because of who we are, our personalities. He's liked me since the 6th grade, so I know he's serious about me. I'm the girl he's always wanted and loved. And now that I am with him I just...love him so much it's crazy! Lol. But I was online and even talking to some people and they always seem surprised we're still together and even talking about our future. My bf wants to join the marines but marry me and start a family with me. So it never seemed odd to discuss our future. We act like a married couple already. But now people have me all stressed and worried, cause they all look at us with sad eyes that basically say "Yeah. Good luck, it won't last." And a few people have said the college years are very brutal on a relationship. I'm terrified it will ruin what we have! Right now, where we're at, I am so in love and finally happy and calm and just proud to be in the relationship I'm in, seeing how we started off so cruddy. I couldn't see someone who deserves me more than my bf. No one loves me more than he does, and I know we're young but I just feel good about this, like it'll last, despite rough times. Do high school sweethearts never last? Do they usually marry but divorce. I'm so nervous now...