When you're embroiled in a bad relationship, there's often a conflict playing out somewhere inside: part of you knows you're unhappy, while another part keeps finding compelling reasons to stay. On "End It Tonight," the Sydney post-punk band Teenagersintokyo does a good job of capturing what that feels like. "I lose myself every time I play your game," frontwoman Samantha Lim sings over pitiless, grinding guitar chords. "In many ways you're right." It's a short line that gets at a complicated truth: on paper, the worst relationships can sometimes look like the best.

The first hundred or so seconds of "End It Tonight" are all brooding, minor-key guitars over a driving dance beat--in other words, pretty much of a piece with the kind of rock music that's been so popular this decade. It's a welcome surprise, then, when the song climbs into an airy, chiming middle eight, with guitarist Sophie McGinn knocking out delicate scraps of melody that wouldn't have seemed possible a moment ago. The effect is like breaking through clouds to see the sun.

It only lasts a few seconds, and then we're back to the main progression and down below the clouds again, but that moment of elevation has given our narrator enough time to see the light. "I lose myself," she sings, "so let's end it tonight." The relationship, having gone on too long, will come to a full and complete stop. The song, having lasted just long enough, does the same.

On iTunes: Teenagersintokyo / "End It Tonight"