I think part of the inherent comedy of AFFC is Jaime starting to see Cersei as his sibling again…. like not his sister-lover but his sibling who says and does things that annoy him and keeps trying to boss him around and who he’s bickering with in front of their uncle…. he’s been thinking of her as first and foremost a lover for years, and ‘sister’ as synonymous w that, but now he’s back and the romance is falling apart and he realises oh shit yeah siblings are fucking annoying