The speaker begins with a small moment of relief: for once, they feel happy. But the second line undercuts it. Someone else, addressed as "you," always seems to find a way to ruin it. The repeated words "away" and "down" carry the sentence along like a slide, so the reader feels the speaker being pulled from a good mood back to "the ground."
The poem suggests a painful relationship, though it never says exactly who "you" is. Being brought down to a place where "you and me are equal" is a bitter idea, as if the only way to be level with this person is to be hurt by them. The ending is the saddest part. The speaker believes they can't smile while the other person is smiling, which hints that the other person's good mood comes at their expense. The mood is resigned, tired, and a little trapped. There is hurt here, but also a quiet sense that the speaker doesn't expect things to change.