From the album The Way She Looks
This is about wanting someone so badly you can't tell if the relationship ever existed or if you invented it to survive. The Northern Lights line isn't poetic flair. It's him admitting he can only see himself through her, and even that version is dissolving. The whole song is stuck in the question mark between memory and fantasy.
I see myself in the Northern Lights / And the way she looks there escapes me
He finds himself in something beautiful and unreachable, then immediately loses her inside that same image. The Northern Lights are a mirror and a vanishing point at once.
Was it all a dream? / Yeah, all a dream, to me?
He answers his own question but it lands like doubt, not confirmation. The second line doesn't resolve anything. It just makes the uncertainty heavier.
So I'll carry you if you carry me / A delusion that is elevating
He names the fantasy as a delusion in the same breath as proposing it. The deal isn't real and he knows it, but he's offering it anyway because the high is worth the crash.
If we could live our dream together / Stuck in this fantasy forever
The conditional tense does all the work here. Every 'if' is another admission that this isn't happening. He's building a world entirely out of what isn't true.
The song never leaves the maybe. It stays suspended between what happened and what he needed to happen, and the need is so strong it starts rewriting the past. By the end you realize he's not asking her to remember. He's asking himself.