Yeh, that scene is the NTR Sue path, where is is upset with you and is inclined to cheat. Will probably lead to losing Sue to Theo in the end.
I had a hard time triggering that one. I believe I used quick start Monogamous Sue > and then there an option to say if she slept with Theo or not ( make sure you say she did) and that worked. For some reason I couldn't triggering it if I said Sue was on a sharing path if I recall.
Weird. It doesn't work on my run.In this new update, you has to turn on sharing toggle and restart a new save(for the best), then choose all the options that upset Sue and choose the option that Sue slept with Theo after Sue spying mc having sex with Scarlet, then you will be on Theo NTR path and this scene will be triggered in this update.
I manage to upset her, the system shows likely to cheat, but still no NTR path.