Honestly, not really.
Most monogamous relationships these days either have already had an infidelity, or will. It's so common now it's a fucking cliche. Even couples going on 50 years or more, have had it. My Aunt, for example, celebrated her 60th anniversary, everyone thinks they have the perfect pristine marriage, yet I happen to know, they both fucked around at least twice.
When I was with humans we had open play, but there were rules, like "Not in our bed unless we both are involved", "no barebacking strangers", etc. Nothing extreme just common sense or deeply sentimental things. But if my partners wanted to jam another human in their ass/pussy, go nuts, just don't lie to me, and say you didn't.
But my dogs? I MIGHT let my male mount a person, but touching my girl will result in the loss of your fingers, and, despite potty mouth talk, I wouldn't actually play with a dog outside my mate circle.