It always makes me laugh, as a single guy, when guys who have someone seem permanently intent on ruining it by being complete d*cks.
Would he have been as upset if you had rudely not fed his friend?
It is most certainly HIM.
If I'm round my friend's place and they're not there or are getting ready; their partners always offer to make a drink or a snack if its time to eat. It is common courtesy and something that is lacking in society this way; no wonder when that is the result.
Without knowing if there was an underlying problem, ie if there has been an instance of cheating it is difficult to truly comment. I would say though that if he is worried that you are going to be having it away with his friend then he either doesnt bring them round or he makes sure that you aren't alone. He raises the problem, he should solve it.