I think cuz she’s a princess and thinks she’s special that he’ll treat her any better??? Like I think she has the problem of “I can fix him” syndrome taken to seriously, girly no you can’t, she’s gonna be in the MC position.
I also confused too but she's still nice so I think maybe as third party she didn't know the whole situation. There's a scene where she wondered whether FL was usually treated like that.
But probably she's just plot device because her personality and situation feel weird somewhere isn't it? she's so nice but married a prince who has personality that doesn't match her, and they don't really seem lovey dovey in front of people. she also very nice to FL but why didn't she do anything before? why now? probably plot.
Its because she thinks she’s special. At the beginning, when our MC gets memories from the old Ariadeline (or however you spell that…), OG!Aria tells the princess Carlotian wont fall in love with her (the princess), and the princess responds with something around the lines of “I’m not as stupid than you”. So yeah, its her huge ego
Why is the Princess going through all of this for that man when she witnessed how he constantly neglected his own wife to pine after another woman? Does she seriously think she can change him or something if she just got his wife out of the way?? Lmao embarrassing