Everybody. Dilemma

I have been engaged for about five months to the perfect woman. About two weeks ago, she received a text after ten p m from a male co worker. She explained that they invited other co workers, but everyone declined or baileda ok. And if you did the same thing, she would be cool with that. I wouldn't be cool with this man or woman. This is not because i'm trying to see jis like a a female thing, and a guy doesn't understand this is not cool.