The speaker is working through the pain of a love that didn't last, or never really began. The opening line is blunt: "i was never the one for you." Right after it, the speaker admits they used to believe the opposite, and the repeated "i thought that. / i really believed that." shows how strongly they held on to that hope. The line "fell in love with the idea of us" suggests the speaker may have been in love with an imagined future more than with the real situation.
The poem then slides from acceptance into hurt and confusion. The questions at the end, "what does everyone else have that i dont?" and "what did i do wrong," carry a raw kind of self-blame. The lack of capital letters and punctuation, plus the short, broken lines and the lone "but," make it feel like thoughts spilling out unfiltered. The mood is vulnerable and sad, with a tired, lingering sense of rejection and no neat answer.