The poem opens by correcting an assumption: the woman it describes isn't lonely, she's trapped, caught inside her own thoughts. She feels time is always chasing her, or failing to leave her alone, but the speaker says time is only trying to catch up. The hourglass image carries the rest of the poem. Comfort, sanity, innocence and life itself trickle away, and the more she grasps at them, the faster they go.
The mood is heavy and anxious, with a quiet sense of helplessness. The speaker seems to watch her from the outside, almost tenderly. The ending is the most striking part. She imagines the clock simply stopping, no more ticking, and the final hour brings relief as the pressure and pain lift. It's an ambiguous moment. It could mean peace, or exhaustion giving way, and the poem leaves that open. Judging by the imagery, the release it offers is the end of time itself, which makes the relief feel both calming and unsettling.