Someone the speaker loves has died, and the speaker is furious about it as well as heartbroken. The title points to Icarus, the figure from myth who flew too close to the sun, and the poem uses his fall as a way of talking about a loved one who seemed to walk willingly toward their own destruction. The key phrase, "you knew exactly what you were doing," appears twice, and the repetition makes it sound like something the speaker can't stop replaying.
What hurts most isn't the loss itself but the choice. The speaker says plainly, "that's what hurts the most," and the poem's one-line stanza makes that admission feel like a pause for breath. The word "left" matters too: the speaker feels abandoned, as if the other person put something else, the thrill of the flight, ahead of staying. The mood is bitter and mournful, with love and anger tangled together. The short, flat lines leave no room for comfort, and the poem ends on that unresolved sting.