[mlangsdorf]

Actual coup. Definitely hadn't thought of it, but it's clearly distinct from assassination or a civil war.

The parliament doesn't entirely legitimize the king, but for purposes of this discussion they represent the factions who have to directly consent to the king's governance. If they say "we made an error, that other guy is king", the current semi-legitimate king is going to have difficulties governing.

I think the closest historical situation might be the Glorious Revolution: William of Orange was in the process of invading, but James II effectively abdicated the throne when it was clear that he no longer had the support of the Protestants in the army and in Parliament. There wasn't a coup or assassination and James II didn't lose in a civil war or foreign invasion. He just left when it became clear that he didn't have sufficient support to enforce his own will any longer. (Okay, he came back later in Ireland but that's beside the point.)