Its hard. I started dating my now-husband in high school, and then he joined the Marine Corps. We were apart for a year, and during that time had only seen each other for two weeks after boot camp and then the week at the end of that year when he came home and we got married.
That year we were apart was our third year together, so we’d already spent two years together.
Its really hard. We actually ended up not thinking about each other during that last month of boot camp (its three months long) because it was just too hard. That doesn’t really apply to you though (all we had during boot camp is letters… no phone calls, nothing but letters).
I think being able to touch the other person is very important. Especially for women, who tend to be more touchy-feely. I don’t like hugging anyone other than my husband, and when I needed support, all I had were his words (assuming he wasn’t at work or sleeping, which was often). Words are nice, but I need the physical support too.
It might be easier if you start the relationship already used to not seeing each other every day though. People often find it easier to open up on the internet. Its also easier to lie over the internet, especially if you don’t know the other person. It may be difficult to develop trust with that person, which means jealousy can easily enter the picture. I imagine if you meet through a dating site, you both are looking for a lasting relationship (especially if you both go into knowing you wont get to see each other much), so it may not end up being a problem.
When you both start to love each other, you’ll probably want to see each other a lot, eventually leading to marriage / moving to each other. You’ll have to consider that you may end up leaving where you are now. Do you have a great job you don’t want to leave (especially in this economy)? Would you be able to leave friends? My friend married someone she met online (I think it was through WoW), and right now the big deal is where they’ll live after college. She wants to close to her family, and so does he, but the families live in different states. If you go into something not prepared, and these things become problems, you or the other person may end up getting hurt.
You’ll also have to consider what you’ll be able to do. You wont be able to go see a movie or go shopping together or anything all the time. My husband and I played WoW together, and would have played games through Xbox Live if I had an internet connection to it. Things like that let you spend time with the other person without feeling like you have to find something to talk about.
I’m not saying it can’t work. It can. Its hard though. I know I’m a little different in real life than online, so I imagine some other people can be that way too. It takes a lot of work, and like @eponymoushipster said, a lot of honesty. A relationship can’t work without trust. And one or both of you will have to move if it does end up working.