Nikhita is one of a handful of dogs that are able max out Ninjas incredible patience.
This picture looks feral, but don't forget that growling, showing teeth, snarling and warning bites into the air are just part of normal communication.
It is not about biting the other dog, biting is always the last measure... no dog/wolf wants to get bitten or hurt. Being hurt could be life threatening and as such needs to be avoided if possible.
Also these moments usually do not last... it is a matter of a few seconds at most before things are back to normal.
I would have stopped it sooner if it was a serious confrontation, but these two were actually just flirting, testing boundaries.
See... all is good again :)