Bringing man after man into the house which causes undoubted confusion and upheaval to the kids makes her a bad mum. The example she sets for her kids through past actions (which they will learn about) will be damaging.
I don't care if she loves her kids. 99% of parents love their kids. She needs to put them first and stop living her life like a circus and going through men like it's going out of fashion. You can't behave like that when you have children.
She is not a good mother for those reasons.