The speaker says they're used to standing outside, soaking wet in heavy rain. It sounds like a small, almost casual remark about weather, but the last line changes everything: "Just like how you treated me..." Suddenly the rain stands for something else. Being left outside, cold and drenched, becomes a picture of being shut out, ignored, or treated badly by another person.
What stands out is the word "used." The speaker isn't shocked or angry in a loud way. They've gone through this so often that it feels normal, like bad weather you stop trying to avoid. That quiet acceptance is what makes the poem sad. The trailing dots at the end suggest a pause, maybe a sigh, as if the speaker could say more but doesn't bother.
The mood is lonely and tired, with a hint of bitterness. The poem is very short, and that bareness fits: there's no dramatic outburst, just a plain, painful comparison that lingers after the last line.