I agree with many of the reviews that have been written so far. The animation wasn't bad but it could have been much better, even within the simplistic hand-drawn style you choose. It is kind of strange that the dog is buried, I think you should have come up with another literary way for the dog to die next to the masters he/she loved. I love the progression of the tree although it's strange that it simply disappears at the very end. I think it would have been more emotionally provocative if you had left a stump with it fallen over next to the graves or a dead husk of a once mighty tree or something.
This flash movie really gets to you though as others have said. It made me think about my own loved ones and made me reflect on my own life. It also depressingly made me think about the futility of it all, that even if we have amazing love like the characters in this movie seem to have, that one of us will likely die before the other and someone will have to bear the ultimate grief of being alone, staring mortality in the face as the most important person in our life dies.
It's personally always been... a sort of fear? regret? or something of mine... the act of leaving the girl I love behind. I feel hopeless at the ultimate laws of the world we live in and anger at the pain and waste.
Good job, I look forward to more of your art.