He is clearly getting abused, but he has already gone so far with this cohabitant
fornicationship that if he stops now, it will have all been for nothing.
She makes him feel guilt over the cohabitant
fornicationship, repeating that she has given all of her to him over and over and what a horrible predator would he be if he still refuses to say the words, "I love you."
She wants to prove her brother wrong, that what she is going through is love and not a cohabitant
fornicationship, but it will be decades before he is persuaded.