This was a terrific story; definitely a keeper! I loved the beginning and end with Robert Frost, which gave it a cozy feeling. The longing of the story was intense; Harry's longing to free Snape warring with his longing to love him. He would've broken his word either way, so I'm glad he chose the noble course, even though he thought he might lose love.
I can imagine that Severus would make his wounded pride exact a high price from Harry. He had very little left to claim as his own, and I can understand wanting those memories left alone. Had he been free to make a life with Harry, would he want it to be said that Harry was a substitute for Lily?
I loved the moment when he realized he would rather have Harry than Lily. It really made the tone of the story, and the tension between them, more exquisite.