海誓山盟挂嘴边甜言蜜语在心间
[hăi shì shān méng guà zuĭ biān tián yán mì yŭ zài xīn jiān]
This nickname reflects a relationship where grand promises and loving words are constantly on someone's lips. It describes an intense period in relationships characterized by romantic vows made with great emotion and sincerity, and also conveys sweetness that exists between partners.