It's Always Sunny in Philadelphia Season 6 Episode 2
Dennis Gets Divorced
An unhappily married Dennis makes Mac throw him a bachelor party and soon he realizes he needs to get divorced. Frank and Charlie also realize they need to get divorced, but neither couple can use their old lawyer due to a restraining order. They call upon Uncle Jack to help them and he's able to give Frank and Charlie an annulment, while Dennis gets stuck with nasty alimony and debt when their old lawyer represents Maureen.
Oh and Sweet Dee learns she's not the only mistress in Bil's life when she accidentally kidnaps his kids.