A voice behind the wall

I live alone in a two-bedroom apartment I bought six months ago. The walls are thin, so the sound is good. The neighbors below and above are pensioners, and in the adjacent apartments there's a family in their forties with a son and a guy in his mid-twenties. From the very first day, I could periodically hear this guy's wife talking, ordinary family conversations: "Dima, put the kettle on," "Dima, it's late, go to bed," and so on. I didn't hear his responses, but I didn't pay any attention to it.

I recently returned from work and discovered my phone charger was broken. I decided to borrow one from this Dima. And it turned out he wasn't Dima, but Andrey. And he doesn't have a wife. And he doesn't have a girlfriend. As it turned out later, there's not a single Dima in the entire building except me.

Now I'm scared in my own apartment. The worst part is that this voice behind the wall keeps periodically talking to Dima.