Pimps and polygamists take over Washington State
Mormons and friends partying at the state capitol
Olympia becomes first Washington city to pass polyamory protections
The Portland City Council advanced similar legislation last month. Advocates say they are now pushing for protections in other Washington cities, including Tacoma and Seattle.

A mixed group or more than one couple sharing a house don't need any special protections for doing so.
Except that it's a party going on all the time, they're “swingers” with the doors literally swinging off their hinges, loud music blasting, and they're doing street drugs and excessive alcohol along with all the sexual promiscuity.
As far as the “landlords” are concerned, they're damaging property and turning rental units into drug houses and whorehouses, and now the whole city has become a gutter district of drug dealing and sexual immorality.