well the doll is modeled off of the trainer . . . so it boils down to what is "cheating"?
At least to Oguri she felt that she betrayed her beloved trainer. I personally would say it's very understandable considering how a trainer would be working all the time and cannot spent all his time with his horse girl. Just pat her head, tell her there's no harm done and carry on.
Even though I have you, I... I...!squeeze...Oh my~(tltr. "ara~")so... squishy... so cute...!I'm sorry, TrainerEh!? Um... uhh...The trainer buying a plushie of you shouldn't really matter, should it, Oguri?But he has the real me...If you try it from your partner's perspective, I'm sure you'll understand!Here ya go! It's a plushie I knit yesterday of the trainer!No, I have the real trainer, so... b-... but...rub rubW-...What's wrong, Oguri...?That day's training
