Closed vs. Resolved Endings
A closed ending ties up every thread; a resolved ending answers the central question. They are not the same thing, and conflating them produces either endings that feel artificially neat or endings that feel unfinished. The central question of your story is the one the opening raised, whether that is 'will she survive?' or 'can he become who he needs to be?' A resolved ending answers that question. The subsidiary threads, the minor characters, the secondary plots, do not all need tying. Readers accept open threads as long as the story's heartbeat has stopped in a way that feels right. Over-closing is as much a problem as under-closing: it signals that the writer did not trust the story to end itself.