Ideally, couples should have discussed and agreed on how to deal with each other’s parents before they got married, but it’s not too late to discuss about that if the parents are causing problems.
I think some men forget that when they got married, they are now the head of their own household. He and his wife have become One - whatever affects one party affects the other. Parents, however good their intentions, are still "outsiders" to the marriage. Some mothers are also reluctant to sever their apron strings tied to their sons. That’s why it would be harder to have this separation if the couple is living with the parents.
Wives, don’t challenge your husbands, don’t put him in a spot where he has to choose between his mother and you - you may not like the outcome. Don’t complain, don’t nag. Rather, try to help him see your point of view. Let him know you need him to protect you. Most, if not all men, would like to feel like a hero to their wife.
In most situations, if the marriage is in order, the husband-wife relationship is good, then it’s unlikely that parents could cause much problems. In some cases, it is perhaps the marriage relationship that needs to be fixed first, rather than the one with the parents.