Surprisingly, this is one of the few songs they have that isn't really about sex. This one is particularly about poisoned relationships. The guy and the girl want the relationship to work, but they just don't love each other that way, hence the line 'make a wish on our sorry little hearts'. The line 'have a smoke, pour a drink' means that the relationship is stressful, and they kinda want to just drink to forget about their issues. 'Steal a kiss in the dark' means that the relationship—or lack thereof—is private, or something they can't let other people see because it's sorta wrong. 'Fingernails on my skin like the teeth of a shark', this part IS about sex, and is pretty straight forward and literal. 'I'm intoxicated by the lie', basically, they're fuck-buddies, but they both either want it to mean something, or they think it meant something. They're basically blinded by their emotions. Now, 'In the chill of your stair I am painfully lost, like a deer in the lights of an oncoming bus', basically means that he's not sure how to act around her. 'Hearts on fire to night, feel my bones ignite, feels like war' they're both pissed, and they're fighting. To the guy, it's similar to war. 'We go together or we don't go down at all', basically means exactly what you think it means. They go together til the very end.