Halo 5 Assassinations: Who is assassinating who?

Has anyone else ever had this happen?

You turn the corner to find your ally is assassinating someone, so you don’t kill them… Just to find out that they were actually on the receiving end, and you could have saved them?

Happened one too many times to me. I’m always “that guy” now who comes up on an ally assassination and “steals” it.

Sorry, not sorry.

I usually just shoot into the mess if I can’t tell. Unless you are right on it or saw the beginning then it is difficult to tell who is doing what. So I just shoot.