I was once very upset with a colleague who co-taught a Sec 2 Normal Technical class with me. It was quite a raucous class and I had planned the lesson but my colleague took it in a different direction which required the class to leave the classroom.
On the way to the venue, I told my colleague, within the earshot of several students, "I am not happy with the direction that this lesson had taken". The colleague acknowledged my anger but did not say anything.
Years later when we discussed this scenario, I asked my friend whether he was upset with what I said. He said, "No because you were in the trenches were me."
The answer was not logical, but to me it was perfectly acceptable. Despite our differences, we were fighting a "war" together.