Why does my boyfriend's mom act like this?

his mom is a B****. But if you love him you have to tolerate it. So just ALWAYS be nice to her. Kill her with Kindness. Believe me she will feel like a REAL *** being rude to you, after you always treat her so nice (i know it may be hard sometimes but just do it.) Don't even make him choose between you guys EVEN if he would choose you. That is his family, and evidently his sibling needs him, because his mom is such a half *** parent.