Yikes - teens certainly can be dramatic. I find one of the toughest things is to remain calm and not feed into the drama. But that is sooo difficult, especially when you are tired or in the middle of something and your teen is ramping up for a showdown.
I can't believe I'm even going to say this .. because I HATED it when my parents would say this to me .. but, you might want to just state that other families have different rules and different ways of doing things and that is OK. But that doesn't mean we do things just because others do them. (I don't know if the boy friend is skipping school or has a reason like a Dr. App't for not attending).
In my school district it is painful for kids to miss a day of school - even if the child is home ill. The child has so many days after returning to school to make up all homework, tests, quizes, etc or they get a zero. Doesn't really make it worth the effort to just stay home because.
Good luck - hope it worked out ok.