all those women tended to be adults and could have chosen to leave

Without the federal government, almost no money exists to fight domestic violence

no other private or public organization has financed anti-domestic violence work as broadly or as deeply as the U.S. government. Without federal funds, the work being done to prevent intimate partner violence, feed families in shelters fleeing abuse or help survivors file for legal protection would not exist on the scale it does today.

The disruption the Trump administration has wrought on this critical public safety and public health infrastructure is unprecedented, threatening a framework built over a half-century. Teams responsible for violence prevention have been decimated, and a reorganization of the Department of Health and Human Services has eliminated divisions wholesale. The president’s proposed budget, as well as the Republicans’ appropriations bill, suggests defunding many of the programs that remain.

This is already an underfunded and neglected corner of the federal bureaucracy. It's been eroded over multiple administrations, via budget cuts and manpower shrinkage. Telling women "if you don't like your partner, just be homeless" is functionally participating in the abuse.

To address your second point: people change. And often times, unresolved issues that started small can get bigger.