Your friend is trapped in a cycle of abuse, he has her convinced that when things go bad it's HER fault. He was at one time nice to her, he love bombed her and then he began his systematic abuse towards her. She loved this guy in him that never really existed and she is convinced that if she gives in and is good she will get this guy back that showed her love. She could not be MORE WRONG. Sadly, this is what abusers do and they choose someone they KNOW they can control and manipulate.

Your friend really needs actual professional help AND to distance from this guy so she can LEARN what kind of trap she has fallen into. She is young yet, inexperienced and most likely has fragile self esteem, but that's because she is young and inexperienced yet. I am very sorry you have to witness this, that you try to talk to her about it and you end up watching her only run back to him to face even more abuse.

I don't know what Canada has to offer in terms of help for this kind of challenge. Your friend needs help like in a woman's abuse center so she can learn about how she is being abused and why it's so important for her to break free from this abusive boyfriend once and for all. He doesn't love her, what he loves is CONTROLLING her, which is why no one even knew about her in his family and why he discourages her from having friends etc. He is actually doing a lot of damage to her right now, and this is going to take her time to first get away from and then to heal from.