I'm in the exact same situation as you, except my gf is 10 hours flight. It takes me around an entire day, or around 16 hours, to get from my place to hers. Plus I've been doing it for several years now.
The situation hasn't gotten any easier for either of us, but in a way, it hasn't gotten any more difficult. What makes a difference is our lives. We're both busy. She tells me that when she's at work, she doesn't really think of anything but her job. Fair enough, because I'm the same.

It's 7:30 pm and I'm heading home from work. It's when I get home where I think about her.
Oh, and we talk every night on Skype for around 30-60 minutes.
Also, we always know when we'll see each other next. I'll probably see her in 5 months.
We also know approximately when the situation will change and we'll be together, and that's in around 2 years. To be honest, we could be together today if we really needed to, but before we do, she wants to hit a career goal first, and she can only do that at home. After that, she'll be 'ready' to move in with me (I make more money than her and her job is more 'portable'). I also want to work and earn my certification, which takes a number of years.
I also could have moved to her country to work, but I would have been paid far less money doing a job I don't want to do at all, for longer hours per day, and I would still live 3 hours away from her. Neither of us would get a lot of vacation time in her country (I currently get 4 weeks), so we would have still been talking over Skype! We both made a choice that's better for us long-term, and that means being apart for now.
We plan on getting married, but life is expensive, so this is a perfect opportunity for us to save money for a house, etc.
And everything EricNau said was right regarding LD relationships, IMO.
