Every marriage is its own little economy, a business of two with a finite number of resources that need to be allocated efficiently. In their book, Spousonomics, authors Paula Szuchman and Jenny Anderson apply bedrock economic principles to some of the most common conflicts in domestic life. Some examples include: Division of Labor (Or, Why You Should Do the Dishes): Exposing the fallacy of the 50/50 marriage split. Some people are better at, say, making school lunches, while others panic at the sight of a vacuum cleaner. Here’s a tip: Do what you’re “relatively” good at and “trade” the rest. Incentives (Or, Getting Your Spouse to Do What You Want): How getting your spouse to finally pay the bills on time is simply a matter of finding the right incentive. Trade-offs (Or, The Art of Getting Over It): The simple beauty of the cost-benefit analysis. Let’s break down that four-day trip to Cabo with your friends. Costs: A grumpy wife, $700 airfare, kids that miss you. Benefits: a savage tan, enough Don Julio to inflict permanent damage, uninterrupted sleep. Verdict? Supply and Demand (Or, How to Have More Sex): Talking your sex life to death, waiting until the kids are asleep and you’re both catatonic, not admitting that lingerie turns you on—all bad habits that raise costs and lower demand. The key to keeping your sex life hot is keeping it affordable.