The speaker has been caught in a love triangle, or at least something very like one, and she is the one who has been hurt. The poem opens with a run of self-blaming questions: why didn't she see it coming, why was she so naive? She calls herself a fool for believing things would work out. That sting of hindsight is the first thing we feel.
Then the poem narrows to a single, stark choice: "Her, / Or me." Putting "Her" on its own line makes the rival feel like a presence in the room, and the short lines make the speaker sound breathless and exposed. The decision isn't hers to make. It belongs to "he," and all she can do is wait. The ending is quietly vulnerable. She admits she doesn't know what he'll choose, and says only that she hopes it includes her. The mood is anxious, raw, and a little pleading, with hurt and hope sitting side by side.