What you're saying is meaningless. In case the female character is not the MC, it is someone who could have a relationship with the MC. And if this character has a boyfriend and is someone who will relate to the MC, it is NTR.
Once again, I urge you to review the definition of NTR. From Urban Dictionary:
Japanese acronym for Netorare, used to define a genre of Eroge (Hentai Game), meaning "Cuckold". In short, the main protagonist's loved one(s) are taken or seduced away from him and the heroine might be willing or unwilling. This is to cause an emotion of deep jealousy on the reader.
So, the Western term for NTR is cuckold. I reiterate, since there is no intimate relationship between the MC and Elaine, there is no NTR.
According to your definition, NTR exists between a main character and any female character anywhere, which is simply ridiculous on the face of it. Therefore, what you are saying is meaningless.