So, I don't know you have actually implemented the actual war or not, but if not then I have general idea on what the plot gonna be albeit it is pretty much a self-wish employment and definitely generic without originalities whatsoever. It just I want to make the war kinda justified when declared. Note that all of these ends up with all the notable female characters in their respective country offering their love to Ryen.
1.Begus
-After several certain events, Church launch coup de etat on Jean and put her under arrest.
-Demi-humans got prosecuted really bad and there is even a rumor of prison turning into concentration camp.
-Ryen somehow got visited by Goddess Yureka and ask him to stop the madness. Depending on your choice during helping the queen with internal problem, the plot will shift a bit.
-If you solve the mine by silver smith, common folk of Begus would help Ryen. If it by fixing the military then Begus regular army will mostly in mutiny and will give intel to Ryen.
-There is mandatory event in Pumumu/Citadel and after said and done, you went and liberate the capital and after several days, queen abdicate the throne and willingly give you Begus after saving her and Ryen take her hand in marriage.
2. Dorgania (Should be done after Luminous Order events and the start of Brexet Isle Treasure events)
-The remnants or the entire rebels (depending of your choice) started a regicide and quickly take over military and replacing it with rogues and greedy turncoats.
-The princess are not killed due to her being popular with common folk. She instead imprisoned and tortured due to her connection to the royal family by rebels who despise them. Kurohime told Ryen this and declared war after refugees crisis coming out of control ( and out of anger toward princess captors)
-You start off at the Orchel as you have the most influence there (and pretty much can send armaments quitely using your trade hub which you built in the village before). And since you either strike a deal/annexed Luminous Order, your army can pretty much come from the south quite easily.
-You continue off toward Rakake and gained help by the foxgirl sisters and continue toward Sriveta, blessed by the Water Spirit for your war.
-You sieged Kagabagui and won, but find out that the princess and the rest of high ranking rebels has fled and trying to escape on a ship from Oceanview Tower.
-Ryen and his party managed to reach them by teleporting immediately to Central capital and intercepting them on a ship from Havaria port (Brexet Isle Event must be start first) and also thanks to Water Spirit blessing making your ship faster than usual. Ryen had several fights with the enemy crews and a bossfight with rebels higher ups.
-After said and done, same story like with the queen of Begus and she will instead live in Kagabagui despite being your wife to maintain public image for you. (Of course you can visit her for "nightly duties" anytime.)
3.Amagal (Should be done after Varea become a queen and visited the Hellhound Village)
-Depending on whether you helped the Earl or King (and afterwards betray them) the remainder should launch a coup and throw Varea into dungeon.
-Meanwhile, Ryen almost got assassinated by a mage and while the mage says "king/earl send his regard). Ryen win the fight and declare war.
-The Amagal turncoats unleashed their goddess who used to betray the Central 6 gods and causing havoc across the country.
-Ryen managed to capture the goddess (and probably put her under his watch.)
-There is cutscene between jailed Varea and king/earl and the latter stated they gave a certain ingredient/reagent to their soldiers in the frontline and it turns out making them berserk and can be transmitted by bites.
-After several fight with Vanguards, the chief of laboratory tell you that she managed to make a cure and tell you to spread the cure through airborne.
-You sieged Manastyr and found Varea. She told you that king/earl with the rest of his army headed toward volcano in order to gain ultimate powerful magic.
-You found him and start boss battle him, unfortunately you lose the fight. However, the Hellhound and the rest of the villagers started to show up and overpowered the king/earl (and in the process beating him into bloody mess *black screen with blood splash and dialogue of king/earl saying "aaarrrggghhhhhh!!!"*
-You freed Varea and same like Dorganian Princess, this time Varea want to abolish monarchy, turn Manastyr into Magic Academy and Institute, and also intend to stay there as Director/Headmistress. (Yes, you can still marry her and "nightly duties " with her)
So, sorry for being too long and probably annoying, it just I feel like this idea can fit into the game and would be nice to see it implemented despite being overly clich茅 and repetitive.