在那个遥远的50年代末，上海某大学校园里，两颗年轻的心被爱情深深吸引。尽管校方严格禁止恋爱，对他们进行了无数次劝导和警告，但这对学生依然坚持彼此。面对学校的压力，他们只好采取最终的手段：男生被“流放”到偏远的大西北，而女生则留在繁华的上海。这不仅拆散了这对鸳鸯，还让他们不得不面对分离。
然而，这两个年轻人并没有因此而放弃彼此。在那片荒凉的大西北，他们共同生活在蒙古包中，每天相互扶持，日子虽然艰苦，却也充满了温馨。直到三年自然灾害来临，那个饥饿与困难的时代到了。
中秋节 arrives, the community distributes mooncakes to each household. The male student finishes work first and brings back a mooncake, waiting for his girlfriend. As dusk approaches, she doesn't return yet. The male student can't help but cut the mooncake in half and eat his portion himself. He thinks that if she were here, she would surely save her portion for him too; therefore, this quarter of the mooncake is also destined to be his.
He then cuts open the half-eaten by him and eats what he believes will be saved for him by her girlfriend. She returns without saying a word until suddenly bursts into anger: "I never thought you'd do something like this! I sacrificed everything to follow you to the northwest, but you couldn't even spare me a piece of mooncake!"
She packs up her belongings and leaves Shanghai again. It turns out that school rules and warnings could not break their love bond while just one piece of mooncake was enough to separate them.
This story tells us how easily love can be hurt or destroyed when we take things for granted or underestimate others' feelings towards us; sometimes it's not about grand gestures or big actions but small moments that reveal our true character in relationships.
The girl eventually understands why he ate all of her share from the mooncake - it wasn't because he didn't care about her as much as he did before; instead it was because they had been separated so long now that sharing such simple joys became an impossible task due to their geographical distance & societal norms at that time which made shared experiences more difficult than ever imagined .
