I've just watched this for a second time and I was intrigued as to the implication of when Scott says this after his outburst.
Do you think he says he was happy teaching her, or this happiness stretches way back to a time long before the film?
Eddie Marsan is incredible.
Personally, I took it to mean that he was happy before he met Poppy, who challenged him and his rigidly lined-up world.
shareI interpreted it to mean that he was happy in his own world.
After meeting Poppy, he's seeing the world from someone else's perspective; as such, it changes the way he looks at his own life. He'd built walls around himself, most likely as a form of protection, where he could focus on his own particular obsessions; the things that brought him contentment. He's convinced himself that these are the only things that really matter. Poppy questions these obsessions and as a result brings the walls down around him.
Suddenly Scott realises that there are people of his own generation that have friends, relationships, fun and adventure. They live their lives and they fail and they laugh at themselves and they enjoy other people; they're not fearful or distrustful or full of anger and resentment.
Through Poppy and the way she engages with life Scott sees something that he's never had and can probably never have and it destroys the perception of life that he's built up. He can't go back to the place where he was happy because his experience with Poppy has shown it up to be a delusion.
I think it's a comment by the filmmaker that sometimes it's better to leave well enough alone; that by trying to help people you can end up hurting them even more. That when people say "I'm trying to bring this person out of their shell" that the 'shell' is often there to protect them; it's not there to distance themselves from others but to keep them from getting hurt (usually because they've had bad experiences in the past). By trying to correct Scott's way of thinking, Poppy takes away from him his sense of security.
Scott clearly did need help, but Poppy (without being conscious of it) goes about it the wrong way and ends up causing more damage than good.
Reading your post was a minute well spent. Thanks for that.
share@ThreeSadTigers After meeting Poppy, he's seeing the world from someone else's perspective; as such, it changes the way he looks at his own life.
I hadn't thought of it that way, as I was more taken in by his rant about her at the end, but it does make sense. Your comment reminds me of a scene in Bridget Jones's Diary: Mark Darcy sees Bridget laughing and having fun on a rowboat, and he becomes aware of the joy that's been missing from his life. Maybe Scott has the same realization, but I don't think it was conveyed to us very well.