The speaker is looking back on a relationship that has run its course, and trying to explain how they feel about leaving it behind. The opening lines paint a restless stretch of late nights, drinking, and a desire that never settles. Other people tell the speaker to stop wasting time, but the speaker brushes them off, caught up in finding the next rhyme. That detail suggests writing may be tangled up with the heartache.
The tone shifts in the second half. The speaker admits the connection was never going to last and calls themselves "the future" and the other person "the past." It sounds confident, though the line about not being ready for a new start hints at some uncertainty underneath. The final couplet is the real point: memories can stay, but the painful feelings can go. "I'm not saying I'm over you / I'm saying I'm over this" separates the person from the hurt. The mood is wistful but firm, a bittersweet decision to move on.