To be honest, a lot of people who don't have a diagnosis aren't necessarily psychologically healthy. Because I know I'm ill, I've had to be more self aware- these people may very well not have a diagnosis, and as a result they don't tend to look at their own thoughts and behaviours much. They just blame others instead. This sounds like your roommate. Unless it was an important phonecall, I would say that it would have been perfectly reasonable to expect him to finish what he's doing seeing as the fridge is communal property. However,people are often unreasonable- the trick is to not let it phaze you. it sounds like you handled it well. I doubt he dislikes you specifically- it sounds like may he have some issues relating to people too, so try not to take it personally.