那年夏天他她执子之手那年冬天她他与子偕老
[nèi nián xià tiān tā tā zhí zi zhī shŏu nèi nián dōng tiān tā tā yŭ zi xié lăo]
It conveys a story unfolding across seasons - in summer, he took her hand ('hand in hand', symbolizing the beginning of love), and in winter, they lived together old age (representing long-lasting commitment). This nickname implies deep affection developing and enduring from a fresh start through to an aged commitment.