Do you get along with your S.O's mother?

There are times where I don't get along with my significant others mother and I was wondering what I could do to change my mind set on it. I normally don't really mind it or care about what she thinks but sometimes it really gets to me. I am also slightly convinced that she is trying to talk my significant other into leaving me. Is there a way to keep the not care feeling or should I talk to my significant other?