https://www.espn.com.sg/nfl/story/_...s-alleged-domestic-violence-incident-revealed
He was convicted. But he appealed for a jury trial, and subsequently paid her off not to appear or cooperate with the authorities:
"Holder and Hardy had reached a civil settlement and that she "intentionally made herself unavailable to the State."
So yes, you can "settle" a criminal assault case. It all depends on your legal team and how much money you have. You are really naive if you think the victim would have seen the case through if it was serious. What is it in for the victim if Hardy gets jail time? Other than a moral victory, nothing much. She's still a battered woman with nothing to her name, and a pile of hospital bills to pay for.
To actually get money out of this, she'll have to put together a legal team and sue Hardy for damages. This would take deep pockets for legal fees, a couple more years with no guarantee of a positive resolution. Might as well take Hardy's money, settle and move on with life.
This is life. Money talks, people walk.