<prompt> Human: I live in a house I own with my girlfriend, who just had our first kid. Normally, we used to split all costs except for the mortgage, and she paid me half of the fair-market rent for the unit were in meaning that shes basically renting while I take care of the cost of the home. Weve been splitting food and bills for five years without a single argument about money.I think we can afford for her to stay-at-home, so long as I deputize her as Queen of Frugality, Guardian of the Cheap, Lord Protectorate of the Wallet. Obviously, I would stop charging her rent and half of bills, and shell need SOME spending money.How do people do this? How SHOULD they do it? I think it makes sense to assess the costs as they are, then decide on the value of her staying home, and pay her the difference each month as spending money.So if her part of costs is 800mo and having her at home is worth 35day 1050mo, then I would hand her 250 at the end of the month for her own spending.Am I being a crazy person here? It seems like quite a leap of faith to just jump into a major financiallifestyle arrangement without some math and ethics going on.EDIT: Sorry I wasnt able to participate much for the conversation in real-time, we were out of the house much of the day yesterday. Ill post responses in-line where I can. Thank you ALL for the feedback.  <response>: If you both think that your girlfriend staying at home is the right choice then Id suggest you make a budget together and see if it works. If you budget spending money for your girlfriend, budget the same amount for yourself. So if her part of costs is 800mo and having her at home is worth 35day 1050mo, then I would hand her 250 at the end of the month for her own spending.Either you live in an extremely inexpensive area or you are seriously undervaluing the costs of good childcare. More generally, this type of analysis seems to cheapen your relationship with your girlfriend. This sort of analysis lends itself to the interpretation of her being a hired hand rather than a partner. I dont know you or your girlfriend, so perhaps this sort of hyper rational, emotionally detached analysis will work in your relationship. But I know I would feel uncomfortable suggesting this to my wife and would feel insulted if she suggested it to me. As I suggested above, and Ill suggest again, you and she should sit down and come up with a joint budget together.And finally, congratulations! 