I’m torn because I want to tell him to leave me alone, that I don’t care about his life, but considering the ‘offense’ this seems too much and knowing me I’d immediately regret it and feel bad about it.

So instead you’ll like youre ruder than you are, hoping he will eventually get it.

You don’t think weeks of having to do this is making you feel worse than perhaps one night of feeling a bit sorry after telling him straight on?

And I know he will appreciate it eventually if the direct reaction isn’t such. You will finally make sense to him. If you’re being rude, ignoring him, why don’t you understand that might make him want to bring you to a normal level of social contact. That he feels he’s done something wrong by just being a chatty person.

Maybe just tell him you’re sorry but you’re not as chatty as him and would like to focus.

And yes, I have also done that to a worker. Told her I’m there to work, not to make friends. Kinda cold? I don’t think so. Colleagues, not friends. Co-employees can be friends but don’t need to.