This happened to my friends dad a few years back, very similar stories & life was like living on the Truman show for him and eventually even me after being so caught up in it. It was really sad to see – pretty much tore his family apart and got really bad to where he lost his job, house, had 2 cars repo'd and has now living without a home for around 2 years. Was a really smart guy too. You have to tread VERY LIGHTLY as your actions will most likely lead them to believe you are associated with the actors thus increasing his paranoia and creating a really chaotic living environment (assuming you live together). Are they dependent on stimulants for work? If so, you may want to order him a bunch of nootropics (bacopa, l-theanine, Rhodia, adrafinil) and possibly find some micro dosed thc pills if you live in a legal state to level out the dopamine in his brain. Nootropics are great for rebuilding basic cognitive functions & there are numerous studies on the being helpful for getting off stimulants. This combination + months of hard self love helped another friend of mine get off the shite and get their life back on track, but he wasn't abusing it so was a very fast recovery. Sorry if this wasn't helpful, I just remember being in a similar situation years ago and feeling hopeless. It's really hard. I hope your partner is able to snap out of it quick before things get super out of control.