I think i read sometime back that Ruo wont change even if you romance him and its something i dont like. You see when i think of changing a RO, my thoughts go back to some classic rpg games. Morrigan in DAO, Viconia in BG2, Shadowheart, Astarion, Laezel in BG3, Nyrissa in Pathfinder Kingmaker, Jack in ME2, Bastilla in Kotor (in a way), Those darkside characters based on whether youre male or female in kotor 2 (forgot their name), Sebille and the Lizard guy in Divinity OS 2, both the girls in Jade Empire who you can either fix, make worse or start a triad towards the end lmao. You even got Invisigal now in Dispatch. All these characters can be 'fixed' in one way or another by the MC throughout the game. Viconia's alignment can be shifted from neutral evil to true neutral via her romance. Nyrissa is a true 'i can fix her' fairytale romance and the best ending of the game is achieved by romancing her. Morrigan is my alltime fav romance (poor girl butchered in Veilguard along with everything else). All this adds so much depth to these characters. Ruo can essentially be one of the 'I can fix him/her' trope but idk whats going on in Niki's head.
Lmao i just realised i just turned this into a big suggestion box of 'i can fix her' romances.