少年非你不娶少女非你不嫁
[shăo nián fēi nĭ bù qŭ shăo nǚ fēi nĭ bù jià]
Expresses loyalty and exclusivity of romantic affection, meaning: a boy won't marry anyone else besides you, nor would a girl wed other than you. It implies an unshakeable and monogamous commitment.