An old abandoned project that I update whenever I feel like it. Give it a read if you're bored. First-person narration, with a tragic slant.
But it's definitely 1v1, single-couple, happy ending.
Yang Yu of the Yang family loses her brother at ten and her father at seventeen. Her life is one setback after another, with barely a moment's respite. Only at eighteen do two blessings arrive at once: she disguises herself as a man to inherit her brother's title and become a general, while the emperor personally arranges her marriage to the childhood sweetheart she's always loved, making her the wife of a second-rank military governor.
A story of two children of military families in the late Northern Song Dynasty saving each other, told gradually from the age of ten.
(The broad historical setting is the late Northern Song, but don't scrutinize the history. The author made up the setting and only borrows a few major events, so it's better to treat it as an alternate world.)
Theme: Never give up on yourself, no matter what.