So you guys began dating when you were 16 and he was 25? Other than the fact that it's statutory rape, the age gap does certainly make a big difference here. It's a little beyond the senior dating a freshman. You guys are at very different times in your lives and want different things. I'm sure what his sister went through has certainly thrown him for an emotional loop and caused him to do some thinking and possibly contributed to the break up, but I ultimately think that what you guys have isn't what he wants or what he has seen for himself at this point in his life.
I don't believe he NEVER wants to get married and I don't believe he NEVER wants to have children. Not for a second. People change their mind all the time. Feelings change all the time as well. I think he is looking for somebody else, somebody different, something he has much more in common with and works around what he wants and his schedule. He moved up there to be with you but it's not working out for him, as rarely these cases do.
Don't take it personal, it shouldn't take away anything away from what you are and what you can provide. Are you in school or going to school? This should allow you to socialize more and possibly meet and hang out with somebody that can fit more with your current life and what you want. I'm not saying you should go out there looking for other guys or to forget him completely. It's not easy after three years, you feel like you just lost a big part of you. But you can certainly focus on having a good time with your friends and honestly when you aren't looking for something, it will completely blindside you.
I hope it helps and I'm sorry. Keep in mind that while you guys may both love each other (even though he said he didn't) that it doesn't always work out because you are at different places in your lives.
Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.