I mean is it really even NTR? You're fucking 6 different women. You're not exactly in a stable, mutually exclusive, loving relationship between man and woman. I guess I only consider something NTR if it's a boyfriend and girlfriend and one of them cheats. I could never see Harem shit as NTR.
Honestly NTR or rather netorare/netorase/netori are kinda hard to define since their literal meaning is netorare = having a loved one stolen to bed, netorase = enjoying seeing a loved one being taken to bed by someone else and netori = stealing a loved one to bed.
Then you have the loved one term which again is super broad since it can involve a sibling, a friend, a gf/bf, a parent, a one sided crush and so on. I mean I always find it weird how it's called NTR if the MC for instance has a sometimes onesided crush on his/her childhood friend and then the childhood friend sleeps with someone else, even if they don't love the MC in that way or is in any kind of relationship outside of being friends then it's NTR.
So I'm pretty sure you can ask 10 different people on here and they will have 10 different opinions on what is classified as NTR or not. On this site however I believe that it's classified as NTR as long as the MC in any way, shape or form is having anyone remotely close to them that they might see as a love interest sleep with someone else then it's either NTR, while if the MC does the same it's classified as cheating, or if the MC is in on it and trading partner then it's swinging.