Thank you so very much for reading my fic and commenting. You seem to have encapsulated the reason I wrote this fic.
There are so many facets to it - Severus's decision had far-reaching implications for both him and Harry, and it resulted in both of their unhappiness, but there was happiness that resulted, for both of them. Of course, that happiness wasn't permanent.
All too often we tend to make decisions that seem to be appropriate at the time, yet when time passes we realize how very flawed our thinking was. This fic is a study into this idea. Unfortunately, we do not get any of Severus's insight into why he did what he did.