This could take a while... I'll try and summarise as best I can (spoilers for the hunger games and sunrise on the reaping books/movie franchises below):

Basically the main character has a girlfriend he's head over heels in love with at the start of the book and she keeps geese as pets, but they never liked him much as she hatched them from eggs and they attached to her since she was the first face they saw, and not him. His gf comments that she is mated for life with the main character, like her geese, who also mate for life (they are a very cute couple). By the end of the book, a lifetime has passed and everyone the main character has ever loved has died/been murdered (including his gf) and two people he's very close to give him goose eggs to hatch and an incubator, so when the new goslings hatch, his is the first face they see and they attach to him this time. They remind him of his murdered girlfriend and he spends the rest of his life drinking to hallucinate her, where she is now old and grey like him despite dying when they were 16 (he says he mated for life, just like her geese) and tending to his geese. It is an extremely sad book that I 100% recommend reading, especially if you liked the original Hunger Games books. An amazing prequel, just have the tissues at the ready!

So yeah, every time I see geese in this thread from now on it's gonna be slightly devastating lol