One of the things this poem is about (if poems can ever be simplified to being "about" anything), is how nighttime, darkness, and the stillness of being alone in bed trying to sleep tend to bring about rumination. The speaker laments and obsesses over the past, particularly a past relationship. She is aware of the "voices of evening," which are all "tinged by terror or nostalgia." Thus, Kizer describes here the ways in which darkness and nighttime stillness tend to exacerbate our anxieties, fears, regrets, and loneliness.
This is a fairly terrifying poem because it is ultimately also about loneliness, especially humans' need for companionship and our fear of being alone. Kizer describes the feeling of what it's like to be entirely alone with these ruminating thoughts and fears. She tells us that "when the moon's creamy beauty is transformed / Into a map of impersonal desolation," there is no longer anyone in bed beside her, "no heavy, impassive back to nudge with one foot / While coaxing, 'Wake up and hold me.'" Kizer describes here a fairly common human longing: to be held and comforted by someone else.
Kizer also speaks to this human longing in the line "Now, when I call out in fear, not in love, there is no answer." She tells us that missing this person doesn't necessarily have to do with love, but with her fear, her loneliness, and her need for human touch and comfort. So, in part, this poem could be commenting on how humans need companionship on a primal level, and how this need fuels many of our relationships. It's also simply commenting on a woman's ended relationship and the loneliness and grief that ensues.
The poem is confessional, with the speaker, a woman, baring her soul, expressing the terror that comes to her at night, and lamenting the loss of her love and the onset of loneliness, admitting that she is altering “our history” to justify the breakup by stating that her loved one, even when things seemed good, was always “withholding something.” We may presume that the “you” of the poem is the departed husband, or lover. The speaker closes with reminiscences of “lovely times” when no was met with affirmation. In the present time, however, she contrasts her fear with lost love, her cries with no answers, her silence with only distant voices. The words all suggest that the speaker’s circumstances have changed, and that everything she now experiences is “tinged” with weeping and nightmares, terror or sentimental reliving of a better past. The use of participles indicates ongoing situations of the past and the present. The participles “coaxing,” “withholding,” “trying,” and “feigning” are all in the past, and these are consistent with the presently perceived imperfections in the relationship. The participles “living” and “weeping” are descriptive of the speaker’s present condition, both indicating the difficulties she is now experiencing.