The speaker lies awake or asleep in a house where the person they love sleeps in a different room, and that small distance feels like a larger one. Outside, or inside the dreams, the sea is rough and noisy, and a waterfall seems to roll along beneath the house. The speaker talks to the water directly, saying "I love you" and wishing to fly with it. It is a hopeful, almost childlike moment.
The second stanza turns darker. A night hawk grabs the speaker by the neck every night, but its swoop "fails," and the speaker ends up falling into a mere trickle of water. The dream of flying never comes true. The speaker accepts this with a kind of weary certainty: "I won't ever fly with him."
The mood is lonely and restless, a mix of longing and resignation. The poem suggests, though never says outright, that closeness and escape are both just out of reach.