It is a matter of integrity and honesty for everyone. But if you know this lady you mention is lying, then God knows too. And He’s the one she should be concerned with.
In the meantime, there is real emotional abuse, and real physical abuse, and real infidelity, and real desertion, and real refusal to support.
Just because someone claims it doesn’t make it so, but we’ve all seen the real stuff, too.
I agree it really happens. I have seen the effects in my family with a cousin. She ended up divorced, after her then husband cheated on her.
But I am much more of a cynic these days.