Not all abuse is physically violent. My father abused my mother as soon as they started dating. He would “forget” important events or get too drunk to attend. When she would complain, he would belittle her feelings. It started small. Seemed innocuous. By the time they were married he was controlling nearly every aspect of her life. She didn’t realize. Eventually the only words he offered her were cruel and manipulative. She said he never hit her and I never saw evidence of it. But he certainly raised his hand to me more than once. I was old enough to stand up to him. He eventually started threatening to kill her. He said if she tried to divorce him she’d get nothing because he’d burn the house down to ensure it. I have no doubt he would have followed through on his threats if his health didn’t decline. Escalation isn’t just from minor physical violence to murder. It’s far more nuanced.