At some point, it will depend of you and your own perception.
Emily is into SPH and will use her ex as comparison to say how small the MC is. Is that NTR? Because that part can't be optional in the story.
For the actual cuckold content, no problem, it will be hidden by the NTR setting. Zoe has also been cleared of cuckolding related dialogues that weren't properly filtered by the NTR setting, so no-NTR is properly no-NTR in Zoe too.