I'm currently in a weird little situation. My partner and I have been together for 5 years but have no plans to marry. (Thankfully, parental pressure is nil.) However, my visa status is based on our being in a relationship Just Like Marriage and I have to produce joint utility bills to prove it. I don't think this visa gives me any domestic rights at all, and if we split up I doubt I'd have the slightest claim to anything, but it keeps me in the country.

It's a great solution, because while I won't entirely rule out marriage, I am absolutely not willing to make that choice for visa purposes.