Boyfriends parents.

My boyfriends parents haven’t made much of an effort to get to know me. My boyfriend and I have been together 5 months and I’ve only met them a couple of times. I’ve recently found out that they are talking to my boyfriend about our relationship and giving their opinions on it and on me which aren’t nice. My boyfriend doesn’t get along with his mum and when it was said to him he told me his response to them was “whatever” and left his house. He says it’s because he didn’t want to have an argument with them but I’m still annoyed that he didn’t defend me. I spoke to him about how I wasn’t comfortable with them talking about me like that when they don’t know me and he just remains silent or changes the subject. What should I do?