This last line is a heavy-hitter in terms of the title and the general theme of the book. Plus, it comes right after Ethan's death and when Ash gives Jules the book she finds in Ethan's study that has drawings of the first night Ethan tried to kiss Jules and she rejected him. And the end of the novel, the book basically looks back and says that life is always imperfect and always just a little bit off. But here's the last line proper for you:
And didn't it always go like that—body parts not lining up the way you wanted them to, all of it a little bit off, as if the world itself were an animated sequence of longing and envy and self-hatred and grandiosity and failure and success, a strange and endless cartoon loop that you couldn't stop watching, because, despite all you knew by now, it was still so interesting. (22.48)
You could probably read this ending in more than one way, so feel free to explore your own interpretation, but we're thinking that this is a surprisingly calm note to end on. It's basically like, life's messy and imperfect and hard, but despite knowing the inevitability of all this, it's still captivating, there's still a reason to tune in. Yes, even if you spend most of your life riddled with jealousy.