Sorry to hear that.
NTR is avoidable at the moment, but you still see one of the characters coming onto another person (that's all at the moment if you choose no NTR). Unfortunately that is the concept of our game - we'd like to keep some champions' characters. So, it will take time before champions like Ahri or Eve become 'monogamous'. Meanwhile, champs like Lux will never come close to NTR.
Hope you understand and if you don't enjoy that content, please find another game!