Here, unrequited love isn't about longing for something back. The speaker chooses to love bravely and give without asking for anything in return. The imagery is all weather and sky: the speaker makes a cloud above the loved one's head, and when that person cries, the speaker's rain falls with their tears, as if sharing the sadness and quietly hiding it.
Later the speaker imagines flying higher than the stars to leave a piece of love there, so the other person can look up tonight and see it as a single small light. That light becomes a companion, a presence that comforts without demanding anything. The final line shifts back to the speaker, who stays far away, dreaming at the edge of the horizon.
The mood is tender, gentle and a little lonely. There's no anger or bitterness, only devotion that accepts distance. The love is real, but it stays unseen, offered from far off like starlight.