Any story can be a happy story if you end it in the right place.
Maybe it's a matter of missing information: the lover never knows her loved one poisoned another to achieve his ends.
Maybe a journey is cut short: instead of travelling further into sickened lands, the hero stops in a small town and builds her fortune.
Maybe a death brings peace: two kingdoms unite over a fallen monarch, so that his conquering hands are not led by a desperate mind to desperate deeds.
The story's greatest turmoil seems always to come from the narrator's quest for a clean end. But people's endings by design are nearly always messy. Perhaps the cleanest ends are only possible when taken out of our hands.
Kafka seems a fitting test of this theory. His stories, also by design, are some of the most grotesque and ill-fated in literature. His heroes must always meet ruin. Their journeys -- begun with little hope -- quickly devolve into collapsed ruins of a narration. They are happiest when stricken by fire. Their heroes are at greatest peace when they cease to exist.
It might be argued then, that any premature ending to a Kafka story would be a happier result than that the narrator makes for himself. The only semi-happy ending I can think of in Kafka's body of work is The Castle. This is because the book ends mid-sentence.
My own frustration as a reader left without an ending eclipsed the middling failures of the struggling beaurocrat protagonist. At least, those frustrations eclipsed the failures of the narrator at that point in the story. My rational mind knew it was a Kafka tale. I knew the protagonist had only misery to follow. But my hopeful mind, with the story mid-flow, could still imagine some fantastic escape. By suspending disbelief -- a skill that even the most rudimentary fantasy-reader must develop -- I could pretend the beaurocrat, still struggling, would find his saving grace.
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Now: imagine your last failed relationship. Imagine that instead of scrambling at answers to a story that had run out of lines, circumstance had taken the question out of your hands. Imagine that you had missed out on a few of your joint final joys. Imagine, too, that all your final failures and heartaches -- save, perhaps, a deciding one -- were whisked away like a small tempest of sand.
What if you could look back on the gutted structure of your relationship and see only the strongest parts still standing?
How much earlier would your story need to have ended to avoid the whole thing crumbling to the dust?
Every story has a happy ending. If you end it early enough.