I do not think any story of them can have any sort of viable resolution without forgiveness on both their parts.
I so agree with this--stories that try to skip over this issue are rarely convincing.
I know HFN has been well recc'd and raved over, but I have to take this opportunity to say that I think it is one of the best HP fanfic stories out there. You achieve that elusive goal of good fan fiction writing--keeping the beloved characters true to their canon selves, while taking them well above and beyond where their creator left them. I found HFN to be a very visual story, and elements of it come back to me in mental "snapshots"--Harry and Snape in the bell-tower, watching the sunset; bald Snape in a baseball cap and sunglasses, riding in the pickup truck. The images and feelings from your story have stayed with me in a way that the original books have not. I'm sorry that you don't plan to write more Snarry, but hope you'll still be writing in the HP universe. If you decide to write some AU Snarry, I'll be delighted to read it!