SAHM with no kids 🤷🏾‍♀️?

This is what I don’t get. My BD got married last year and his wife is a “housewife”/“sahm”, BUT they have NO children! We have children and they’re with him half the week. So she gets to be a sahm to MY children when I have to work because he pays no child support. Idk …does this seem odd that she’s calling herself a sahm when all her kids are grown.