While the news of Jude Law and Sienna Miller's $12 million London love nest purchase this week wasn't a total surprise — they've been hot and heavy again since last year —  I will say the pair are going about the engagement/marriage/house routine in a bit of a backwards way. For most people, buying a house with a significant other is an ultimate commitment; cosigning your name on a 30-year mortgage is not something to rush into in this economy if you're not truly dedicated. One might even argue that finalizing a divorce is easier than selling your house these days.

The trouble is that if you separate, one of you will wind up paying a mortgage on a house you're not even living in. That's the case with Charlize Theron and ex-boyfriend Stuart Townsend: after they split up, Townsend was living in their co-owned Malibu beachfront property, which they wound up trying to rent out for the tune of $30k/month. I'm guessing they didn't have much luck there, considering that property is now on the market for $7.5 million.

Those who can afford a hefty mortgage, like celebrities, might consider buying a house with a significant other just as an investment or a business transaction. But for the rest of us, who spend a majority of our paychecks on housing, having a ring on your finger before you start playing house offers a little more insurance against winding up in Theron and Townsend's situation. What are your thoughts on buying the house before the cow?