If you are a guest in someone's house, for example your boyfriend's/girlfriend's house do you try and mind your language?

I lived with someone who had the worst mouth on the planet, and eventually I began speaking like him. He embarrassed me to death in restaurants, and basically everywhere we went, because he would pop out the eff bomb in front of little children. After I left him, I made a real effort and returned to my normal way of speaking, and he is off dropping eff bombs where ever he happens to be. I don't know if people who are raised by wolves are able to control themselves. 😖