“in 23 of the 30 largest U.S. cities, there are laws that limit occupants deemed “unrelated,” defining a “family” only as a group whose members are related by blood, marriage, or adoption. In St. Louis, no more than three unrelated persons may live together. In Sugar Land, Texas, the limit is four. Private homeowner associations may be even more strict. In the Chase Oaks Homeowners Association in Plano, Texas, a “household” can comprise no more than two unrelated persons, though there is an exception for live-in employees.
Those who would like to form a household of five single adults or multiple unmarried couples in order to share costs are not permitted to do so—no matter how many bedrooms are available. These relics stand in the way of allowing the widowed, divorced, and never-married to build households.”
https://reason.com/2025/01/17/regulations-keep-millions-of-bedrooms-empty-during-a-housing-crisis