Responses
The question is how he is saying it. After all it could mean a lot of different things depending on the emotion.
I feel like he was saying it in a sad way because it wasn't the first time he found out he had a spy on his building, and since it looks like he is having feelings for the other dude he may be disappointed(?)
i took it as he almost ment himself.
Sad about the professor saying that he shouldn't have trusted a human, but like the last picture tho