I think the whole soap and ascending rank argument Diana makes is about being greedy or not. She thinks people should not aspire to go from a commoner to a noble because it'd be greedy of them and that nobles are inherently greedy. Hence her trying to make her tea parties "frugal" (serving cheap tea in this one and commoner treats on the previous one) like she's throwing in the nobles faces that she has a higher rank she earned and she's not greedy like them. She's a self-righteous hypocrite who wants to show everyone how superior her sense of moral and lifestyle is (if not how could she, a commoner, be chosen by god and the crown prince). She's can't handle being even the tiniest bit wrong. She faults Hestia for manipulating Kael when actually she and Heli were the ones who drove him to the brink of despair and as hestia pointed, they both had their status elevated by marriage. Diana is a bitch who thinks only she is worthy
kahir looks so good in those casual commoner clothes (づ ̄ ³ ̄)づ