I cannot give you exact advice, as I haven't looked at that part of the law recently. There have been some updates last year regarding marijuana use, as VA has started to become more and more liberal towards Marijuana.. I can, however, guide you in the right direction..
Here is what you need to do:
A) Ask a lawyer what the law states. Lawyer should know the most current law. The only thing I know is that with drugs in play, you don't need to provide any notice to the tenant. You can directly file for eviction. Now with COVID situation, you have a different mess on your hands..
https://www.nolo.com/legal-encyclopedia/tenant-defenses-evictions-virginia.html
B) Do not get involved in dispute between the two tenants. Just because the guy hasn't paid doesn't mean he is smoking weed. I have heard everything from weed smoke, to loud music, to roaches being reported by the tenant who is unhappy. If she smells weed, she needs to call the cops.
C) Do not try to evict them yourself.. Self help is the worst thing for landlord. You need to follow the legal process.