Whoa! Spoiler Alert!
Boy, they will have almost 300 years to live together after those 8 years. They were given a vision of their life after that time, and when you get to feel the worst is far gone, you realize it has been nothing compared to the endless happiness that lies ahead. That's what the parents made them feel before the trip back home. About Amicus, the wolves were indoctrinated to have blind faith in the parent's guidance, and they see them as powerful and wise (almost godly) beings, so it's not odd that Amicus thought he could trust them to keep the MC safe. They literally brought him back to life after all...