Yes, household income is typically used because you only pay rent once per household, not twice. You typically only have one set of expensive appliances, furniture, etc per household, not 2.

Also, household size has historically fallen -> https://twitter.com/Mark_J_Perry/status/1307408040686235650

You can also just ignore dual-income households and look at the data for single-income households, it's essentially the same (if not better) -> https://twitter.com/ernietedeschi/status/1308775197311467520