cuz many see sharing as ntr aka heaven forbid if li has sex with some1 else.
and exactly THAT is the big problem: people THINK.....
I know you know better, so please don't feel personal offence when i am saying "according to their definition (sex with anyone else) it should also count as ntr when Dee having intercourse with Elena. I am NOT on Elena path - so what? Is it now ntr? Dee had sex with someone else?......
People need to grow up and finally learn that ntr is NOT simply "having sex with non-love-interest or see another dick".
Look:
The heck, people call even the long past memory of a sex scene between Dad and Ashley (inSunshine Love) as ntr even MC was a child then and Ashley was NOT a love interest at all that time.
Some people just are too insecure and don't want to see ANY other dick at all -> but "i hate dicks" is more to type than "i hate ntr", i guess