Great piece of artwork there...
I think the overall tone represents the sense of liberation that comes when one is able to finally let go of something or someone that has been in his mind for so long, and the thought brings not only sad memories, but also a feeling of longing for that past one knows will never return.
But it also represents how one acknowledges that this person has brought true unforgetable feelings and would like to honor them by remembering with kindness and joy, instead of focusing on the "stillness of the wintery years".
The true sense of forgiveness expressed, along with the understanding that "holding on to hurt runs its course / Like every season " shows that the speaker knows that this dark feelings are something needed to be able to let go of this past, and start thinking of the joyfull times that once were the only thing that mattered.

Great work, pal, definitely will follow and keep on reading your poems.