no matter what happens in the end with what this manufactured timeline and such, I only wish to see the princess reunited with Sieg in one way or another.. definitely no moving on to other men, and no moving to the afterlife for Sieg, and no being content that she is "technically" adventuring with her husband through Lynn.
one thing would be the princess being done with her wish, and having Lynn's mind be assimilated with hers and they'd continue as one person, or even Lynn just disappearing as she kinda fulfilled her purpose in bringing Siegfried back to her. I'll even take the princess dying and her soul going into the sister genderbending sword and then Lynn can wield them both and they can be together in spirit form idk...