若以笙相许则以沫相濡
[ruò yĭ shēng xiāng xŭ zé yĭ mò xiāng rú]
Based on a classic tale, it's like saying 'if we vow to be attached to each other by words, then we would support each other with everything we've got'. It refers to deep commitment or loyalty in relationship, especially when two people choose to live together amidst hardship.