Salam,
I know many Muslim landlord (in the West). Their apartments are typically non-smoking and no pets, and they will ask you about your employment when you contact them (like every other non-Muslim lanlord). According to the Fair Housing Acts this is seemingly the maximum you can get away with before it falls under discrimination. That being said, people clearly violate these rules all the time (e.g. Chinese buildings).
What confuses me is the following... Presumably these Muslim landlord are renting out their apartments to boyfriend/girlfriend couples... or else they wouldn't be able to survive in the rental market. One would assume that non-married couples are engaging in Zina. Regardless, it is free-mixing nonetheless. Furthermore, they likely rent out their apartments to gay couples, who are likely engaging in Sodomy, or lesbian intercourse.
What does Islam say about this (from a Fiqh perspective)? Should Muslim landlord be able to discriminate in order to have NOT provided the tools necessary to perform immoral sex acts (I.e. housing)? OR Should Muslim landlord be forbidden from discriminating in regards to housing (since shelter is considered basic human right in the religion of Islam? Does it depend on how many listings are available in order for it to be considered reasonable or unreasonable (If many apartments are available, then you could argue that it's not really denying housing, but rather it's deferring housing? OR should Muslim landlord simply assume the best in their tenants, so that a self-proclaimed gay couple is really just two straight dudes hanging out?
This question brings up more questions than it answers. Our traditions condemn living alone, as this is a huge gateway to commiting sin... so would it also be wrong to house any non-straight non-married couple? Another question to add on could be regarding transgenders and whether or not they are the sex that they say they are (when considering this question), and whether or not you should refer to them by their preferred pronouns, shake their hands (which sex are they really?) etc...
Lastly, breaking the law is Haram in Islam. Discrimination based on sexual orientation, gender, marital status and/or relationship status is ILLEGAL in most western countries, such as Canada.
But is it also Haram to break a law that you cannot easily prove as violated in order to follow God's law more closely?
Anyways, for the sake of this question, we will assume that this discrimination is legal... despite it being absolutely illegal.
TL;Dr...: My main question is the following: Is denying housing to straight non-married couples, and gay couples HARAM or HALAL?