I would be peeved more so that he didn't communicate about what his idea of the night off would include.
Personally- if he had said, would u mind if I go out with my mates- It wouldn't bother me. I'm happy for him to have time with friends and I know that at any time I could do the same. But if I had said 'I was hoping for us to do something together' he would have done that instead or arranged a night out with mates another time etc.
It's all about the communication and respect to ask what the other person wants and needs as well as fulfilling your own desires in a non selfish way.