A few people asked in comments and trackback where Linux would fit into my tortured metaphor.
Linux (on the desktop, at least) is the psychotic girlfriend.
She seems exciting at first and you pour an enormous amount of energy into the relationship, but she keeps demanding more and more, and she never gets any more predictable. You'll find yourself awake at 4am arguing with her about where you left the toilet seat. And while the fact that her idea of a good night out is a trip to McDonalds means your wallet is thanking you, you end up wishing for someone a bit more refined.
If you're lucky, you'll come to your senses and do your best to keep her at arms length. If you're unlucky, Stockholm syndrome will start to kick in...