The speaker opens with a blunt self-judgment: "I'm a let down." They don't soften it. They call themselves "the one that's always a setback," as if failing other people is a settled role they play in every relationship. The word "always" makes it sound less like a mistake and more like a pattern they've come to accept.
Then the tone shifts a little. "Yeah I'm pretty lonely" is said casually, almost with a shrug, and that offhand voice makes the admission feel more honest and more painful. The last line, "but that's the thing about love," is the puzzling one. It could mean that loneliness and disappointment simply come with loving someone. It could also be bitter, a way of brushing off the hurt. The poem never says which, and that gap is where the mood lives: tired, wounded, quietly resigned, with a faint sense that the speaker still believes in love despite everything.