Boyfriend refusing money from his brother

Question for you all today. My bf has his only brother who has done very VERY well for himself and refuses to accept any money from him. Now my b/f does good enough as a middle class earner (like myself) but so many other family members of him and friends say he is insane for not taking anything. My bf has no debt, almost has his home paid off, has both vehicles paid off, and decent savings. And his brother keeps pushing him to take some and now he is asking me to instead, to which I am like..."oh hell no!" I'm not letting money ruin my relationship. Anyone of you had or have a sibling or other family members do this and not let up and what did you do to stop em from badgering you or your spouse/partner? I am thinking his brother wants to use it as some level of control, but I am not saying anything to either of them about it.