THe story from the sister is completely worthless.
a) what do you expect her to say?
b) what could she possibly know about Jake and Tanya - other than nothing, which is depth of the story
c) what a waste of bandwidth
The story from Tanya is interesting ONLY if she has hard evidence that they were together after the engagement. But even then it'll just be ED-II, and in today's morally vacant society most people won't care or will make excuses, and Vienna clearly wouldn't care because this is the best gig she will ever get and she isn't going to split over something as trivial as cheating.