It’s hard to tell whether Prufrock is really in love with the person he is talking to. He speaks about himself a lot, and he ignores her, or "us," for most of the poem. Maybe he’s too shy to speak his mind, although "cowardly" seems more accurate. There are a couple of points where he almost overcomes his massive fear of rejection, especially when he is standing on top of the stairs and wondering, "Do I dare?" (line 38). But he’s so vain and so taken up with trivial pleasure like coffee and peaches that it’s hard to believe that the feeling he has is really "love." It might just be lust or just a strong attraction. Whatever it is, the feeling never goes anywhere, and Prufrock is left to drown with his would-be beloved in the deep, deep ocean.
Prufrock is not just some stalker. He truly believes his beloved has sent him signals that she likes him, but he is worried that he might be misinterpreting her signals.
Prufrock can only experience love through other people, at second- and third-hand.