Yeah, that's what I'm talking about. It's really very frustrating.
If you're just talking about the diplomacy screen, that's what the war is called. You didn't start the war, your vassal(s) did, and their purpose is to depose the king of Ireland. Unfortunately, the diplomacy screen doesn't take into account that you are being
attacked in this war, but it's not too hard to realize that the results are reversed.
From the screenshots that have been posted, it doesn't look like your allies are actually siding with your rebelling vassals in combat. It's just how the war is displayed in the diplomacy window.