But it’s a fictional story. Yes, deal with the trauma. Yes, deal with the post-war. Yes, have an epilogue that’s not necessarily the happiest and that all glory is fleeting and all that.
But as a STORY? As a piece of fiction that requires resolution? Ending it on a cliffhanger that you have no intention of resolving is narratively dissatisfying and a big middle finger to the people who got invested in the characters and wanted to see that conclusion.
To which George RR Martin may reply also with a big middle finger.