@broadsword80
Its not just about him though. There is no such thing as a 1 man side to a civil war. If it became war, their entire family would be involved by obligation, and also their supporters. All of these people are MC's current citizens. In other words, they are the ones who he is meant to be protecting. Usually duels were used to not involve the citizens in combat between nobility. But this guy does not seem like the one who would bet everything on a duel with the current king who also is the strongest person he knows. He knows he cant win the 1v1, so he would only choose war, where he has a better chance (it still is basically 0%, but he does not know this). Also, a war would mean putting Yuria against him because of the obligation to her fiance. Best thing for MC is to wait for the guy to fuck up (which is an inevitability), then publicly destroy him. Basically shame him out of power. It saves his reputation, while also will not involve innocent citizens, and if his rep becomes destroyed along with his influence, then Yuria is free to break the engagement, since it is only a political marriage. Once one side looses their power, their is no longer a reason to hold the marriage, since at best your own reputation remains the same. At worst, it is destroyed also.