Let's say you've got two teenage daughters...you give them a solid set of rules to live by while under your roof. One daughter is a constant pain in the ass and breaks the rules 68 times but because she's so pretty and so nice (you secretly favor her) you let her get away with it every time and never punish her. The other daugher is not so pretty...in fact most folks think she's ugly (secretly so do you) she sees the first daughter always getting away with everything...so she tries it too...everytime it happens with the ugly daughter you punish her...she's grounded, can't use the car, etc...then finally after the 16th time ugly daughter breaks the rules you kick her fat ass out of the house before even your wife comes home to debate this with you. 

Now, when your wife finds out she's very upset with you but you say "Hey, I could not take anymore. She broke our rules 16 times and I told her this can't happen while she's under our roof. So, I told her that's it you're out! How else would she ever be able to take us seriously!"

     In the meantime, pretty daughter breaks curfew again because she's out having a threesome with a couple guys from the football team. You, of course, forgive her and welcome her home with open arms at 6:30am the next morning telling her..."Honey, we're just glad you're safe."