When I initially started renting I did the same, lawnmower, weed eater, rakes and all things needed. The tenant failed to do regular maintenance my house looked a mess. At lease signing we upped the rent and added a lawn service. We found this to be the easiest solution. I work in insurance and so does my wife. While you can write a lease to say it is not your responsibility it doesn’t stop a suit. We didn’t want the hassle.

I would follow the terms of the lease. I would charge the late fees and demand payment. I use turbo tenant and I do not allow partial payments. I would also send him a written notice reminding of the due date and letting him know payment will be due along with late charges to prevent further actions.

If it doesn’t seem like it will end I would let the one paying partial rent out of their lease. For the remaining tenant I would set some firm ground rules about decorum and expectations. You can’t/want be a mediator, but you can require respectful communication interactions. I would update my lease to reflect that policy.