it could just mean he's shy? I can understand him wanting to keep a distance if he not only works with you but lives with you: I assume he's not looking for any personal relationship (and you don't say you are, either), and the amount of eye contact he deploys may be much the same as he'd deploy with any landlady.
I'm not sure people actually make as much eye contact with others as they think they do. In my experience, it's something you maintain with occasional glances rather than constant staring.