using vulgarities is due to the way he is, it doesn't matter if
its his gf he's talking to, or his parents he's talking to, if he's
used to using it, it doesn't make a difference to him. However, he
SHOULD try to refrain from using them, and MAKE a point to try. if
he's not doing that, then its not really tat great.
Try talking out with him, settle this together, tell him that u're
sick and tired of him treating u this way, and if things don't
change, you'll have no choice but to find someone else better.