Wow. Like others have said, I think he's very confused. He's becoming a teenager and certain things happen around that time. But he also is an orphan with no parental figures to replace his own until they came into his life. Maybe he's been battling these thoughts in his own mind and even wanting to talk to her about them at night? But hearing him say those words is both extremely heartbreaking and sweet. Though, I still think they need to sit down and have a very real and truthful discussion on the matters brought up before.