Kids turn on parents for a boyfriend/girlfriend all the time.  Parents don't want to see their kids with someone they feel is unsuitable and their kids seem to think "unsuitable" is what they want.  So starts the war.

Parents have to walk softly that they are looking out for their child and not controlling. 

I have to say that this works both ways a lot of the time.  You see woman get some creepy boyfriend and drag them home to live in the house with their kids when they don't even know the guy themselves.  Half of these kids that are abused were living in homes with mommy's creep of a boyfriend who just happened to have spent 10 years in prison for rape and is a registered pedophile.  Ofcourse mommy didn't "know" because she didn't take the time to know.