Colleges

I heard somewhere that there are colleges some where that won't admit gay students and put all kinds of pressure on the students not to illegally marry each other. They won't let the students of the opposite gender in the same dorms as each other and, well, yeah. You get the picture.
Other than the anti-gay marriage rule, all of the rules seem reasonable At least, there is some good intent for the student behind it. Having a baby in college is generally not a good thing. However, I wonder what would happen if they said, "You know what, do it if you like. Having a baby with you is fine." And put all the work and energy funneled into the old rules into learning, which is generally what you go to college to do.
 It makes you think, if an approach like that could (Possibly work in a school) then why not in a government? WHy not stop the wars in the middle east and put the effort into getting out of things like the debt that takes up more than 1/60th of all the money in the world. Thats more money than any individual could ever hope for. It's more than many countries have put to together. So why not forget killing people in far away countries and focus on helping the people of our own.
My dad told me that you can't just back out of war like that, but why not? Is it against some unwritten law that the opposing country needs to be battered into submission before any peace is reached?