Versions of sin in Brideshead Revisited

To my surprise- in yesterday's post I speculated that the Charles's affair w childhood friend Julie was a "screen" for his homosexual attraction to her older brother, Senastion, but as the chapter in the third and final part of Evelyn Waigh's Brideshead Revisited continues we see a year or two down the road that Charles and Julie remain in a serious extramarital relationship.  Both of them are pretty much estranged from their spouses yet both also go to some lengths to keep up the facade of a marriage: Julie has to or so she thinks protect the reputation of her politically ambitious husband and as for Charles it seems easier to keep up the facade rather than unravel the marriage. Neither he nor wife Celia seem to care much for each other and his estrangement from his children is actually appalling. This section includes a strange chapter w C and J spending some time at her family's eponymous estate when her mysterious brother, Brideshead or Bridge (!) appears out of the blue so to speak - he's had no role in this narrative other than as an example of priggish vacillation and career failure (he thought about entering the church but is unable to do anything substantive or meaningful w his life).  B announces that he is engaged to marry - a woman he met through her late husband w whom he shared a passion for collecting match boxes, his on,y real interest!  He also says he's unable to invite her to Brideshead because C and J are living there in sin. This provokes both of them to anger, understandably, and few deserve it as much as Bridey, but part of me thinks he has a point - not the "sin" but their complete indifference to the lives of others - spouses , children, family -and their lack of values. C at least is committed to his work as an artist, but it says something that his main subject is English estates on the verge of demolition, i.e., a celebration and commemoration of a vanish way of life - and good riddance to it!