Declawing is actually an amputaion of the enitre tip of the toe, it can be a very painful recovery for the cat (which the cat would try and mask any signs of pain) and can be physically and mentally damaging. I'd tell your boyfriend to get his toes and fingertips removed, walk on his feet without any walking aids and see how he likes it!
Hope you get through to him and everything works out well in the end for you and the cats!
