The poem turns loneliness into a person: a cold, controlling husband the speaker never chose. She describes his stare on her neck, his grip on her, and the way he keeps her stuck in a corner at prom while boys who want to dance with her walk off confused. The wedding metaphor is the clever part. She can't remember the ceremony, the cake or the gown, which suggests loneliness crept in without her ever agreeing to it, and now it feels impossible to divorce.
Her feelings move from disgust and desperation to hope. She longs for someone stronger to pull her away, and in the end she throws down her ring and escapes, with help from one person. The closing mood is proud and relieved, though not fully triumphant. Loneliness still "looms by," so the poem seems to admit that it never entirely disappears. She just refuses to belong to it again.