I'm kind of in the same spot with my relationship of 2 years. It was great until a few months ago when things stated to slip downhill because of various things. I finally had a talk with him about him about how I wasn't happy and how something needed to change otherwise I was out. Story of this week: I knew he was off to another province soon (last we talked about it was months ago and I couldn't remember the dates) so I asked the other day when he was going - well I learn he's already been gone for a day. Not a "hey, I'm leaving soon for a couple weeks and we've barely seen eachother for the last two months, maybe you want to have dinner/get together/something before I go?" Or "hey, I'm leaving tomorrow/today". Not a word and I haven't heard from him since I learned he had already left, and I don't know when he's back either - I'm assuming a week or so. I'm less than thrilled and it was the last straw. He's stopped putting in any effort at all and I don't have the time, energy nor inclination to hang on anymore. I'm unhappy so I've decided to end it.
Moral of the story: I agree with everyone else. Either sit down and say we need to work on this and change something or be done with it. I tried the first and it made no impact whatsoever so I'm deciding to end it. As Druydess said, it's probably just stringing out the inevitable, that's what happened with me. If you're not happy then it's probably best to end it and move along.