Good to know, though I'm wondering how will you pull this off for Rita, Lori and others?
We can't say right out there will be absolutely zero cheating in the strictest sense of the word. Already Lincoln grabbed his Mom's Boobs in chapter 2 and she ended up enjoying it. Some people might consider that to be cheating.
Just as some people, for some reason, see Clyde showing off his progress with Vanessa as NTR.
So depending on your definition and player choices there might be what some consider to be 'cheating' in a sense.
What we can say is there will be absolutely zero EMOTIONAL cheating. If the player decides to continue the Rita Storyline at no point will Lynn Sr die, at no point will Rita say she thinks Lincoln is a better lover than Lynn, no NTR type of emotional Shenningans.
Lincoln has the option of getting some in depth 'sex education' with his Mother. Special 'bonding time' if the player pursues that. But at the end of the game, Rita will still be married to Lynn Sr and see him as her primary lover, partner, ect.
As for Lori and Bobby.... That's going to be a big part of Chapter 3.
And your choices will have permanent impact on the outcome for the rest of the game.