I've been together with my missus for 4 years. That included every day together for a year in Australia. We both 21, together since 17. Last July, I accepted a job out in Ireland....so long distance relationship!! :/
She's about to be finishing first year of uni.
Still going strong though, speak every day, she comes to stay sometimes, I fly home every so often.
Not a position you'd want to be in.
I guess you could say I'd be scared of the relationship ending, but then I don't think about that, I think about the future, and family etc.