This is what I think happened.
I think they both lived, Middie and Triton. I think Middie fell for a long time, and that she landed at the bottom of the abyss and found Triton badly hurt, but alive. I think she saw in him the shadow of the boy her treachery slew on the battlefield long, long ago, and I think she vowed she'd not lose this love, too. And she didn't. At least that's what I think. She worked hard and she saved him. And when he woke, free of fever, his broken bones mending, she told him everything she remembered about herself and he told her everything he felt. And she listened without fear, and accepted his love and gave him her own in return.
When Triton could walk again they explored where they had landed and discovered a maze of tunnels. And in those tunnels, hanging like cobwebs, were the ghosts of all the men who had come seeking the Snow Queen, and who had died at the goblins' hands. Ralph was there, too, and Triton wept when he saw his friend's ghost., who could never leave the place where he died because he'd forgotten his old life, and he couldn't find his way out of the tunnels.
Middie and Triton did not know the way, either, of course, but they had hope and they remembered the world above them, so they gathered the ghosts and led them. As they walked--or drifted as the case may be--Triton, who still had the men's memories stored in his own head, told them who they were and about the lands from whence they came and the ones they left behind.
I don't know how long they walked, Triton talking, sometimes playing his flute, Middie singing, the ghosts listening, but I think they found the tunnel opening. And then the ghosts drifted away like dandelion fluff, to be in the hearts of the people who loved them.
And Middie and Triton looked into each other's eyes, and took each other's hand, and walked out into the sweet golden sunshine.
When Mother Blomst finished telling the story she drew a deep, long breath and leaned back in her rocker, her hands folded in her lap. She smiled at her children.
“But did they ever go home, Mama?” russet-haired Katerina asked. “Middie couldn't, I suppose.”
“No, she couldn't. And neither could Triton, I think,” Mother Blomst replied. “Not the home he knew, anyway. There's some things you simply can't go home after. Your home is where you're loved, though, so anywhere Middie went with Triton would have been home to her.”
“So what did happen afterward?” demanded Trowa.
Mother Blomst looked keenly at the boy who looked nothing like her or her daughter, the olive-skinned boy she had found in a basket one winter night many years ago and raised and loved as her own. She said, looking at him, “I think they did what most people do when they love each other and are free to love. I think they had children. I think their children had children. And who knows, maybe there are some people who can claim them as ancestors alive in the world today.”
“But what about the goblins?” Trowa went on, oblivious to his mother's scrutiny. “Could they ever get a new Snow Queen?”
“I think,” said Mother Blomst slowly, “I think that as long as there is war in the world, then there is always a chance some little girl or some little boy will be forced into the sacrifice Middie made. But there are Tritons, too. And that's a comforting thing.” She kissed her son's cheek, and then her daughter's. “So, what do you think?”
The End