The narrator was scared by being in a committed relationship, and took out his anxiety on his ex-partner, making her a target of his emotions, or “putting her in [his] cross-hairs”. He claims that he did so without really knowing better (“taking aim without knowin' it”).

After stealing her heart, he is now feeling guilt for what he’s done wrong to it since (“dripping blood”), and he can’t think of anything to right what he’s done wrong (“with nothing to dry it”).

A much more gruesome way of saying he stole her heart at first sight.

Iris = the part of the eye surrounding the pupil, where color is found.

taken from the Cold War Kids song this track samples.

http://www.youtube.com/watch?v=snQW28vYH8s

the “hang me up to dry” and “rung me out too many times” lines go along with the “drenched by her melted cold shoulder” and “soaked in sweat” lines at the end of each verse.

The narrator’s ex-partner tries to give him the cold shoulder as a punishment for what he’s done/said to her, but she cannot stay angry with him, therefore the cold shoulder “melts”, which in turn drenches him in metaphorical guilt, knowing he does not deserve her forgiveness.

“Puppy love” is compared to being drunk, and now the “buzz is gone”, so the initial blindness of new love wore off (or they became “stone sober”).

The narrator cannot continue the facade of pretending they have a healthy relationship in public.

They built up a relationship with each other only to “burn it down” over time, and filled each other’s proverbial “cups” with feelings for one another, only to hastily “slurp” it all out without thinking, taking it for granted.

The narrator says things are not how they once were in their relationship largely because of the gradual absence, or “truancy”, of his interest in maintaining a commitment.