The speaker feels invisible. They describe an "outer body experience," as if they've stepped out of themselves and are watching from a distance while they try, again and again, to win the attention of someone who won't even glance their way. The repeated "I watch" makes them seem stuck, helpless to change what they see.
Then the poem turns. Having failed to reach this person, the speaker starts searching for a reason to live, and admits that they always hoped that reason would be this person. That line is quiet but heavy, showing how much of their sense of worth was tied up in being seen. The ending shifts the tone from longing to a bleak kind of acceptance. "Angels and demons aren't meant to be" suggests two people too different to end up together, yet the speaker doesn't know which one they are. The mood is sad, lonely, and uncertain, with a little self-doubt left hanging at the close.