Boyfriends mom

Recently me and my boyfriend have started a sexual relationship. It was a big step for both of us. I’ve met his mom and his met my parents. However, I feel since our sexual relationship started, his mom has started to dislike me. I have social anxiety and so I don’t particularly want to bring it up when we talk. I just feel as if now this relationship has started, she’s going off me a lot. That’s the last thing I want. She’s also said that she wouldn’t expect that off someone like me. I’m quite a quiet individual. I just feel like I’ve messed up. I don’t know what to do or say. Someone help!!