deduction:

As far as we know, the family doesn't consider it mean-spirited because they don't know she feels differently. Saying, "please don't talk about politics or about my boyfriend- you are hurting my feelings or making me uncomfortable blah blah blah" shouldn't be that big of a hardship unless her family are completely inconsiderate a-holes.

I would argue that they've already proven themselves to be inconsiderate by constantly insulting her boyfriend.

I'm sorry, but if I were dating a guy with different political beliefs than my parents, they wouldn't mock and belittle him.... not because I specifically asked them not to, but because they're not jerks.