The speaker is scolding themselves. The title, "Stupid, Stupid," sets the tone: this is someone who let their guard down and now feels foolish for it. The poem suggests that someone, or something, they believed had stopped, perhaps a source of harm, has started again. They had allowed themselves to relax, to "breathe," and to believe life could feel safe.
The image of "rose-colored" eyes is a twist on the familiar idea of rose-colored glasses. Here, the speaker's hopefulness is treated as a flaw, a kind of blindness they now regret. Notice how small the lines are, too. The short, plain sentences feel tired rather than angry.
The final couplet is the bleakest part. "No matter how long it lasts, / the peace always ends" turns one disappointment into a general rule. The mood is weary and bruised, and the poem leaves us with the sense that hope itself feels dangerous to this speaker, because losing it hurts so much.