It's easy to get frustrated with victims of abuse who don't walk away or can't, and eventually write them off as a lost cause. That attitude, however, serves to further isolate them and gives credence to their abuser's narrative that the victim is worthless or unlovable.
It's not up to me to save my friend. I couldn't do that even if I tried (I have tried), but I can be a consistent source of caring, concern, and guidance. Maybe it will help him find the confidence and strength he needs to leave one day, maybe at 70 he will wonder how he is still with her.
Either way, each of us needs people in our lives who love us without condition, who reflect back to us our true, beautiful selves.