In Tamil, we have a proverb that roughly translates into English as
If the mother-in-law breaks the pot, it is just clay . But if the daughter-in-law breaks the pot, it is made of gold!
This proverb is funnily (and sometimes very sarcastically) used to highlight the conflicts/difference of opinions between mother-in-laws and daughter-in-laws in the very early stages of a marriage.
In South India, arranged marriages are the norm and in such a setting, the bride typically takes considerable amount of time to adjust into the groom's family. Suppose, if there are any confrontations/ disagreements very early in a marriage between the bride and her mother in law and if the groom is highly supportive to his mother (and his family), this saying is used by outsiders/family members of the bride. In essence, they are accusing the groom for not taking the neutral ground and showing partiality towards his mother (the girl's mother-in-law).
Unfortunately, my research for an English equivalent drew a blank.