What is the theme of "The Love Song of J. Alfred Prufock"?

"The Love Song of J. Alfred Prufrock" is about alienation both social and spiritual. Prufrock is an awkward, lonely man who is going through the motion of life without really living. He seems to be connected to no one, despite addressing the reader.
The settings reflect the speaker's loneliness, either by reflecting it (the "half-deserted streets" and "muttering retreats") or contrasting with it (the room where the women "come and go").
Prufrock seems to be seeking companionship, particularly romantic companionship. He is attracted to women, but feels he is too ugly and pathetic to arouse their attention.
Prufrock wishes he had the power to "force the moment to its crisis"-- that is, he wishes he could take effective action in his life and make things happen, whether it be a relationship with a woman or anything else. However, the final image of the poem, of the speaker and the person he is addressing drowning, closes out the piece with an image of inertia and stagnation.

Although "The Love Song of J. Alfred Prufrock" contains many themes, perhaps the most central one revolves around how Prufrock’s anxieties have rendered him completely incapable of any meaningful action on a social, sexual, spiritual, or even intellectual level. This inertia, or what some have referred to as a form of paralysis, only heightens Prufrock’s feelings of loneliness, impotence, frustration, and disillusionment. Throughout the poem, which is part stream-of-consciousness, part interior monologue, Prufrock bemoans how indecision has been the root cause of his many missed opportunities in life. Described as thin, balding, and socially inept, Prufrock is a man who goes through the motions of living—moving through the rituals of society soirees and teas like an automaton, meting out his life in “coffee spoons”—instead of actually partaking in life or in love. He is also at his most neurotic when in the company of women: likening himself to a pinned insect, he feels that he is nothing more than an object for their derision.