Re: needing to be sure he’s an addict. That’s not where the boundary needs to be drawn, it’s way beyond that because:
I have a boundary about people in my life taking prescription drugs that are not prescribed to them by a doctor.
I have a boundary about having illegally obtained drugs in my house for any reason.
I have a boundary about shared finances and everyone pulling their own weight and being transparent about where the money is going.
Stealing is beyond the pale.
So For me, it wouldn’t matter if he was actually taking them, their presence in your home is a huge violation and puts you at risk. The lack of money with no reasonable excuse, the stealing. None of these things are acceptable even f he’s not a drug addict.
He can make excuse after excuse. But none of the excuses are ok even if true.