It's been a while since I've seen it, but I think I remember the
ending pretty well. One thing I wanted to mentioned, hasn't the character development in Don Bluth films in the past 10 years looked almost completely identical?! Well it has! Most notably between the characters of Thumbelina, Anastasia, and Titan A.E.
Also, in case you didn't know, Thumbelina is voiced by Jodi Benson, the voice of Ariel. After Cornelius is frozen I think the little animals help thaw him out or something like that and while Thumbelina has to spend her winter in the burrough with the mole and the mouse, voiced by Carol Channing, she escapes when she was about to be forced into marrying the mole. She finds her friend the bird in the hole injured and when she discovers that he can fly again, he helps her escape. When they fly around the fields and meadows looking for Cornelius she about gives up hope until he finally shows up and finds her I believe. The fall in love again and are married by the fairies and her mother the human comes to see her off, and they all lived happily ever after.
That is essentially what happened. I can't remember the exact details, but now you know!!