There is one BIG issue thou, and it's the stage the story is at, if one wants to be as objective as possible the issue is the pacing and the fact nothing really happened before the possible NTR scene between Theo and Sue (+ Lucia).
Season 2 starts with Randall being at his worse, not working, not fixing his phone, not speaking to anyone... who helps him? Only one person, Theo, who sees the state his best friend is in.
It's also through the conversation between Theo and Randall that we see the return of Sue, and Theo knows how much Randall is "suffering" for how things currently are.
At the same time Sue comes back, she's in pain too, professing she's in the wrong, telling the reason she ran away is because she feared to become again the slut that (in her opinion) caused the death of Randall's father.
She keeps crying and, no matter what path we are in, she keeps professing her love (and ok also lust) for him, also highlights how in the months she's been away she had NO sex.
Dessolos is right, if we really neded an NTR scene for Sue, it could have been for example at the gym with the black dude, or with someone completely new, having it happen with Theo is the worst kind of choice at this stage.
The scene is not bad per se, I agree if one is on an NTR route (which btw was only the Max route in S1) it works, but not with no build up and based on players choices that have nothing to do with it (a bit more upset about the work situation and telling Sue she's hot rather than beautyful).
EDIT: because I always forget to mention 1 crucial thing, there's another issue, we (players) are given NO choice not to shag Scarlett, which is what drives Sue to go for Theo (if the other conditions are met).