The speaker is caught between admiration and self-protection. They begin by saying the person they're addressing is exactly the kind who inspires poems: someone whose kind words and beautiful soul keep the speaker awake at 4 am, turning them over in their mind. The line break after "thinking" lets that sleepless, drifting feeling hang in the air for a moment.
Then the word "but" turns everything. The speaker admits this same person is someone they'd "hate to hate," which suggests a worry that things could go wrong, or that the person could hurt them. So the speaker tries to keep a distance, to not get "too attached." The last line gives the game away: it's "much too late." The feelings have already taken hold.
The mood is quiet, honest, and a little wistful. The short lines and plain language make it feel like a private thought admitted late at night, half confession and half resignation.