That is called Cucking not NTR also, she got technically raped in this case because tricked to believe it was you while blindfolded while it was not, you consented and ended up allowing it to happen, that is not NTR and she has not been stolen from you, on that side note if you go with Vanessa and you choose to smash Vanessa you technically did a swap effectively turning it in to swinging with 1 unknowing and unwilling partner in the mix with no idea of that taking place and 2 if anything Joe is the one getting not only cucked but also NTR'd because at the end of the day, She is anything but loyal. However the MC himself ( in the term and definition of what is actually NTR ) is not getting NTR'd in ANY scenario, in order for something to BE considered NTR, you must have had/own it to begin with and essentially effectively losing it and them moving on with whoever it is that they were "swinging/cheating/swapped" with, So in the early part of the game if you had not officially gotten in a relationship with Ann and she ends up with the bartender or whoever else, that is not NTR as she was not your girlfriend to begin with.
Same goes for any of the females around, Same goes for getting Cucked, if you are not in relationship with any of the girls and someone else has been smashing them even IF you ended up watching and crying about it ( as the MC ) they are not getting either cucked or ntr'd, they are however being a voyeur. So if there is anyone actually getting cucked in any way shape OR form it is is Joe and if we want to go in full technical terms, in that specific scene, Vanessa is essentially very much okay with her boyfriend smashing her friend as she herself does not consider her relationship with Joe to be anything serious or of any value, but that would still mean in this case she is essentially also getting "cucked" however she negates that by offering to get intimate with you on the couch, meaning she agreed to a swap weather Joe knows of this or not and you because you are in a relationship in this specific scenario are cheating/unconsented swap.
So no.. no NTR.
Edit: The fact someone needed to facepalm to me explaining the context of the meaning of the 3 letters actually gave me a laugh, because I realized that most of the time people need to facepalm themselves to reset and jumpstart the braincells that are slacking
, can I suggest you try slamming your desk with your face instead, might help cover a more broader area.