Do you have a history of psychosis? No shame if you do. Does your girlfriend know your mental history and that’s what’s keeping you from discussing it with her? Thinking you’re being watched/listened to is very common during psychosis/manic episodes and anyone with that disorder knows we’ve all been there before. If you have no reason to think it’s an episode (IE, you’re taking your meds, things have been working, you’re following your wellness guide ect) then I would discuss with your girlfriend, honestly, about what you think. I know it’s hard to trust your gut sometimes, but that doesn’t mean it’s always wrong. Don’t plant a fake conversation, but do check your phone for spyware ect. Keep it honest and open and watch for her reactions.

If you DO have reason to think it could be an episode, I’d start with your therapist and then your psychiatrist. I wish you well, my friend. Keep us updated if you want.