天长地久有我陪你x地久天长有我伴你y
[tiān zhăng dì jiŭ yŏu wŏ péi nĭ x dì jiŭ tiān zhăng yŏu wŏ bàn nĭ y]
It's like declaring, 'I will be with you as long as heaven and earth last, x (in one way); y (in another).' Expressing deep loyalty and commitment in a relationship.