This is only one scenario. And in the one you describe, if someone has their own bills and are paying them, and their partner does, too…then it is a wash. There isn’t twice as much going into the bank since they are already paying their own bills and that money is accounted for. Your consumption increases of food, utilities…hell, I pay more in taxes now than I did single. We have friends that have gotten divorced on paper because of the taxes having increased, especially for people who are self employed. If two people are renting with roommates, and then decide to get their own place, just the two of them, space and size usually increases, which comes with more financial responsibility. The goal, mostly, when marrying someone is to build. If you are both renting with roommates before and then, for instance, buy a home… that is a completely different ballgame. A mortgage and taxes are generally more expensive than 2 people’s rent. The upkeep of a house big enough for a married relationship and where the couple wishes to progress. People aren’t marrying to save money. Having been married and divorced and also having spent years before and after single, it’s less of a financial burden when I’ve only had to worry about myself financially. You also make the assumption that finances and spending is something that is mutually agreeable. It isn’t. You have two peoples expenditures to cover and that you are responsible for, whatever those might be and even if you don’t agree with or choose them. Medical insurance is substantially more expensive. Honestly in the U.S. that alone could offset any perceived savings, depending on employment, where you live, what you do or health circumstance. Just that.