absolutely. Be There. It's all you can do. Setting ultimatums doesn't work ("if you don't leave him soon I'm going to stop covering for you at work") and insults don't work ("you stupid cow, putting up with that") and you've got to be really careful about sounding superior too (the difference between "I don't think he should treat you like that" and "I'd never let anyone treat me like that"). Trying to persuade or force someone to leave their abuser, much less report them, is a bad idea... you can only let them know that there IS an escape route if they want it.