<human>: Can you provide a brief rundown of the text in within 3 sentences?

I started rooming with this guy a few months ago.  My boyfriend vouched for him and said he was pretty cool.

But whenever I am in the common area of the house he talks to me about random things. If we are talking he will change the subject at hand to some bizarre theory of his even if we are talking about something important such as rent.  

 He doesn't have a filter to his thoughts and says whatever pops into his head at the moment.  It doesn't matter what I am doing.  This has had the added side effect of preventing me from talking to him about anything personal(for fear he might tell someone else) and I avoid being near him now.
<bot>: Roommate talks constantly and it's getting on my nerves.  How can I stop it without hurting his feelings?