Issue: There is a person in my life who is constantly putting down my spouse. How do I deal with this?
Insight: It would depend on whether it was an insult or a concern. If it was an insult, then you may have to evaluate the relationship you have with this person and see if it is worth keeping this person in your life.
If it was a comment out of concern for you; then the first thing I would recommend is, pray through what that person is saying and see what God has to say on the topic. God may or may not confirm this person's concerns. If there really is an issue in that area you could try bringing it up with your spouse. If your spouse does not respond favorably the best thing to do is pray for your spouse in this area.
Secondly, you may want to share with that person, that you understand this issue concerns them, however it undermines your relationship every time they talk negatively about your spouse. Ask them to take their concerns to God in prayer instead of constantly bringing it up to you. That person could also confront your spouse directly, if this is an issue that they are really concerned about.
Lastly, remember to forgive this person, I am sure they mean well and are just trying to look out for you.
I strive to help others by being a safe place for others to ask questions and pose issues they face.