While people can be our friends, they don't necessarily have that deep compassionate relationship where you'll love and be for each other no matter what.
From my experience, as I live in a above-average-economical solitude city, it's quite common to take friendships superficially and just hang out with someone because they have no other choice. One friend invited me for a film after not being able to invite others. Another friend wanted to meet up with 5 people including him, and when 2 couldn't and we were left 3 including him, he didn't want to hang out anymore.

It sounds weird that someone would ask to hang out with you and then get frustrated when you accept. What was his exact reaction? This has me curious...