I wouldn't really care that much. It might not be my first choice but whatever. In reality, there isn't a hell of a lot you can do to stop them if that's what they want. Telling them not to date x,y,or z person will only make them want to do it even more.
It's best to make peace with that and hope they don't come home with a total piece of shit. I'm glad I don' have a daughter. Total nightmare.