Is It More Important to Respect Your Parents or Your Wife?

From Holiness in Marriage (#740) by Rabbi Avigdor Miller: 

Q: Is it more important to respect your parents or your wife?

A: If there is no conflict, you have to respect both. Of course parents are given a different kind of respect. However, if parents interfere in your marriage, it’s your duty to steer them out politely, diplomatically to steer them out and tell them please do not talk about my wife. Please. Put your foot down, don’t let them interfere.

"Al kain yaazov ish es aviv v’es imo v’davak b’ishto — Therefore, a man forsakes his father and his mother and he is loyal to his wife" (Bereishis 2:24). Your wife is like yourself, and therefore you cannot allow your parents to talk about her. Also, not one of the two should talk to their parents about their mate.

Never talk to your parents about your husband or about your wife, unless you can say compliments. If they’re going to say, "but, but," don’t say anything. Never complain about your spouse to your parents. That’s a major error. You’re bringing them into the picture. You and your wife, more or less will naturally get along; even if you’re not perfect., you’ll get along. But once there’s an input from the outside, that’s already artificial input, it’ll spoil the whole machinery of marriage.