"Chelsea" never called the police on her abuser, which meant also making excuses when he put her in the hospital. This was largely because she didn't want her family finding out about her situation (abuse-induced shame isn't just prevalent -- abusers count on it). Also, he was an ex-Marine who had guns in the house as well as severe PTSD, and she knew that a restraining order or a night in jail would just piss him off. Oh, and he was dealing drugs out of their house, so she assumed she'd be entangled in whatever charges resulted from the police discovering that. "Ironically," she says, "my new brother-in-law is a police officer. Even he admits that it might have made it worse in the long run ... There were so many reasons to not get them involved, and I don't regret not calling them."
"Ivy" did call the police, and frequently, but it didn't always go well. To understand why, you need to get some context. When it comes to domestic violence calls, an arrest is only made about 36 percent of the time in the U.S. (12 percent if the victim is male.) Less than half of those arrests result in a conviction because the victims will later withdraw or recant their testimony, often at the "encouragement" of the abuser. This has been a long-running issue in law enforcement, as police have a reputation for declaring the situation resolved once the aggressor has cooled off. (It was once common to show up and the tell the accused to "take a walk around the block." To this day, they often won't take further action if the abuser has left the scene before they get there.)
As a result, some states have passed mandatory arrest laws which require or strongly encourage police to haul somebody to jail. That's the case where Ivy lives. The problem is that, absent clear physical injuries, there's nothing stopping an abuser from claiming to be the victim ... and Ivy's ex was very good at acting like the calm, rational party. "I called [the cops] the night he threatened our baby and then kicked me over when I bent down to pick the baby up. And then they came out and arrested me."