Loved one with weed addiction…

My bf of about a year has always smoked somewhat regularly. I don’t partake in it, and I try to be understanding of it but lately I think it may have gotten more frequent and has worsened his moods in his day to day life. He told me he mainly takes it to help his anxiety as he lives with a difficult family member and has to interact with that family member throughout the day, but I’m worried that it’s starting to take a mental toll on him. Recently he mentioned a situation that made no sense to me whatsoever, and it seemed based off of paranoia, as he was afraid someone was possibly following him. He’s always kind to me, but in this instant he almost believed I was involved and wanted to go through my phone immediately and became extremely agitated when I said no. I know he smoked before seeing me, and I’m worried his continual use of it is causing paranoia side effects and possible mental health effects. I’m not sure how to help though or what to do? He says he’ll quit smoking regularly once he has his own place and is away from that family member, but that could take a while, and I’m worried about his behavior now. Any advice would be most welcome. Thank you!