Communication is key!
If rents are not paid for ANY reason, the burden fall on the tenant.
Normally if a tenant doesn't pay, even for medical or some other valid reason, they can't stay and could get evicted.
It really has nothing to do with the landlord, but with the tenant....in most cases the tenant has agreed to pay and has signed an agreement that if they don't pay....for any reason, they could be asked to move out or evicted.
The landlord or manager in turn typically has an obligation to a lender to pay their mortgage. If they don't pay, they could get the building foreclosed on.
There's usually a lot more to the story than individuals disclose, but then again it could be as simple as....they didn't pay so they can't stay.