she behaved like a better sister to dyan in this world bc the empress of the future literally said "man i wish i was nicer to you back then", so she knew what to do. here, she has no clue why future!kuhn and future!her had such a terrible relationship, so ig that's gonna make her feel antsy about this whole relationship
Yeah and just a glimpse of his cold attitude towards her made her heart ache so much so how would she feel if she still continued this relationship knowing how this will eventually break her.Also the way he looked at her in her dreams has planted seeds of suspicion in her mind as this whole romance could be a plot to make iron king the emperor,as she now knows that kuhn is kaligo.
Sienna is working so, so hard to be a better empress and a better sister than the dream!version of herself... Why is she hung up on Khun's divorce? Why not....Just try to be a better lover too? Seems like the logical step.