My point is simple: at least one male and one female is required or the human race would not exist, whether they're married or not.
The sheer fact that homosexuals have to use other procedures involving people outside of their partners and other hoops they need to jump through, is a clear testament of what the purpose of intercourse and marriage is NOT about.
Sure, you can have sex and get married for reasons other than procreation, but what would happen to the human race if EVERY single person didn't want to procreate?
Then, the purpose of sex and marriage would again show its head -- for the survival and propagation of our race.