I think we're both dancing around some of the same issues, yes-- my initial thought had been towards, in particular, the use of family ties for alliances and cementing political ties.

Being given a divine mandate to essentially break that rule might be considered a combination of punishment/sacrifice... And as she became more politically and civilly powerful thanks to her Domain, a tacit admission that she was a foretold rule breaker and therefore untrustworthy, staining her family and works by association.

i admittedly also did it because "character fated to do like... The worst thing possible socially" is just an incredibly fertile space.

ETA: And like-- I think arguably just as important is how the Asters take it, and I'm not entirely sure how that would work out.