First if she needs to remove children from shared house, police should be involved. There are legal procedures how to do that. If she did that in secrecy, without her partner consent, that is kidnapping by definition.
Second point was reaction to this:
> Taking your children out of an abusive relationship is not kidnapping. If my wife were abusive, I'd leave and take my daughter with me. I'd fight for full custody in court.
I am just saying good luck with that as a men in US.