Of course they can work! The doesn't make it easy though.
I was always one to get tired of someone really quickly--within weeks, a month or so tops. Basically before I ever really knew the person. For me, being around someone I hardly knew too much from the start was like overkill. When I started dating my husband, I was really swamped in college and didn't have much time to devote to a relationship, and not long after we started dating, he started working out of town during the week. So basically I saw him on Saturday night. Then he started working out of state, cross country for months at a time. I honestly think that if that had not been the case, I would have lost interest in him too. So it was really a blessing in disguise.
If you guys have been dating for 2 years already, then it seems like you have a pretty solid relationship that could last if you make it. Nothing in life is promised, there are people who have been married or together for 10, 20, 30 years that come to realize it just ain't workin' out and go their separate ways. Any relationship is only as good as you make it.