待你婚纱落地我必短裙相依
[dài nĭ hūn shā luò dì wŏ bì duăn qún xiāng yī]
Wait until you walk down the aisle wearing your wedding dress; I'll then wear a short skirt beside you as a friend/partner. It implies a promise of staying together through changes or supporting the person at a significant moment such as marriage.