.. Shane and Rachel got married. So the takeaway was, IMO, supposed to be that she fell for him quickly, and he popped the question quickly, leaving her little time to evaluate or maybe even realize all his shortcomings. Or to come to terms with them.

Then the show also made it a point to point out multiple times how busy everyone was planning the wedding, which IMO is very realistic. So she was swept away by having her "dream wedding" instead of having that time and energy to be able to figure out that Shane is aggressively douchey.

So the honeymoon was clearly the first time she'd had time to just clear her mind and spend her energy on *him* and he immediately proved himself to be the worst, at which point reality hit her and she started to re-evaluate whether or not she'd made a mistake.

People get divorced within weeks or months all the time in this country and I have to imagine the above scenario isn't super uncommon. A woman swept away by a rich white kid who gives her everything and proposes quickly, only to equally-as-quickly realize after the mayhem clears that she's made a massive mistake.