I mean her becoming a cock slut who enjoys any kind of dick is more hotwifing than doing all the steps of 'corruption' with less than a handful of guys over a time period of several months. That's how you can catch feelings.
The things we don't get to see is a slice of their every day life. Maybe they're vibing together like no one else in between escapades and it's nothing the best fuck is ever be able to challenge.
If she does something they didn't 110% agreed on - well there's always room for miscommunication. Every good story needs a little wiggle room though, to surprise the player. Their rules are a framework, not the completed house. The game already does a lot of backtracking to explain every minute detail of every encounter.
People forget that Laura is a fantasy...
She's not bound by IRL emotions, feelings, etc.
She's perfectly capable of getting dicked down by multiple dudes without catching feelings...
Which makes some of these comments even more hilarious, because that was her entire reasoning for adding Oliver...
So she could avoid considering Nathan a 2nd boyfriend, and just be the cock slut GF the MC wants her to be...

She's not going to suddenly fall in love with Oliver and leave the MC.
She just likes Oliver's dick...
The most difficult scenes/pics for me in this VN/game, are Laura 'lovingly' kissing Nathan...
Those are some very emotionally intimate moments she has with Nathan... But folks worried about Oliver NTR...
In the last few updates, Laura has shifted to being Ashley's main competition for alpha slut...
And I think the whole point of adding
Nathan's new GF is to clearly show Laura isn't 'jealous' or emotionally invested in Nathan as a 'romantic' partner/LI/BF...