I think the emphasize here should be on the last part... "he SHOULD BE grateful..." but realistically, all his believes are turned upside down, he faced a huge personal crisis, but he still believes in the Codex of the organization, he fully trusts the leaders and what they stand for... of course he will not do a 180 turn and LOVE you for destroying EVERYTHING he holds dear and has ever known for most of his life. He gave everything to the Brotherhood.
In a real world scenario, your boyfriend would dump you and never speak to you again, for destroying his people! It's a mind set, who cares what they are, it is who they are when they identify with the group.
And yes, that's a good anology!
@ IIamaRCA: I'm not sure though, if that would be true to Danse's character though. If you destroy the BoS, I could imagine that he would be so mad and so distraught that he would never be able to stand being around you. Sure, they kicked him out, but he still believed in them, still believed they had noble intentions and honorable goals. No matter what you (the player character) feels about the faction. If you "love" Danse, then you should respect his love and devotion for the BoS.
So maybe Danse shouldn't be fixed, but the player...