The game is clearly designed that way to save time. It means the Dev can reuse content for both main routes. If he didn't do that, it would likely take much longer to produce each update, which I'm perfectly ok with, since I'm only interested in the cheating route anyway. Whilst technically there are two different routes, there isn't really twice as much content as you indicate. Through much of the game it's the same content, but with a somewhat different context.
I suspect that Riley will become less guilty on the cheating route as it continues to develop? She's already starting to develop somewhat of a dark thrill, from the mere act of cheating on Mike. The more this continues to excite her, the less likely she is to be concerned about the consequences. On the cheating route, she's much more likely to drift away from Mike and thus view the cheating element differently. And if she subsequently chooses to work for Jake, which is basically sending her down a path of criminality and prostitution, that is likely to change her perspective even further.
