Sounds like your BF's mother is hoping you will be getting married to her son soon so that she can really call you her DIL (daughter in law) which is really the point in time that is usually considered to become part of the other person's family.....

I know how difficult it is to live around someone who is overly sensitive & in order to keep things going smooth, you have to walk on egg shells....my mother was that way & I got to the point where I just got fed up & refused to care anymore because it just became too much work.

I think it's important to not be overly one way or the other & really try to understand where the other person's sayings are coming from in a more positive light.

Best wishes with all your relationship issues