
it's kind of an odd translation, um, what he says in the original is more like a grouchy suggestion that "Ah so you would cheat with any other puppy, huh??" with "cheating" being used in the over-exaggerated sense of "paying attention to anyone else counts as cheating >:T"
it's not supposed to be meant as him accusing the Yoon Chi-young of anything weird ;;
I feel like some people need to learn the difference between "confidence" and "conceit," because in this context, the girl leans heavily towards one of them more than the other.