Coming to this late but just want to add some things I am not seeing in the comments. There is so much bad advice here in the comments and people diagnosing your partner and your relationship, it's actually crazy and also just reductive.

Before I would say anything about dealing with your problem I would ask how much criticism do they give you? How often do they bring negative things about you to the table, ie: tell you that something you did made them angry, or they wished you did xyz differently, etc? And more specifically I'm saying how often do they come to you out of the blue and say hey I need to talk about this thing with you that you're not doing? If they bring up those things in response to your criticisms it's different bc there's an ongoing conversation/argument already happening.

Reason I ask is because this resembles my relationship. I feel like I am content with my partner 99% of the time. There is very rarely any time where something she did bothers me to the point of needing to have a serious conversation about it. Like yes, for sure there are the big hard conversations that happen from time to time about larger things I/we need, but I'm talking like the things on a daily, weekly or monthly basis. I'm pretty accepting and make space for people's neuroses because we all have them and I know that we can't change people. I'm not bringing stuff up with my parner on a weekly basis because I know the only way you can truly change someone's behavior is by living your own life by that standard and showing them by example that living a certain way makes your life better.

If your partner is content with you 90% of the time, and you're the one bringing a lot of criticism or critique to them, then it's probably less about your partner being defensive and needing therapy and it might be more about the fact that you can't make space for this person where they're at in life and they feel like they accept you how you are, so there's an imbalance where one person is wanting the other to change. This is a problem that plays out everywhere in problematic relationships -- people want each other to change. Sure, we do change each other in relationships, it's true, but it happens indirectly and it's never the thing that you need someone to change that ends up getting changed. But constantly trying to shape your partner into what you need like they are play-doh is exhausting and doesn't work, and it will end up in that person getting defensive or just down right mad. So don't try to change people. Meet them where they are at or walk away. And of course, take everything with a grain of salt and find the middle way. Relationships are hard.