Wow – with friends like Lord Henry, who needs enemies? This hedonistic, selfish aristocrat has the whole world at his fingertips, and, rather than doing something good for humanity, he simply goes about his business in a totally self-indulgent manner. Nothing seems to have any meaning for Lord Henry except his own pleasure. Even his so-called friends don't really matter to him once he's tired of them. For example, Basil, who's supposedly one of his best friends from university, disappears mysteriously for months at the end, but Henry doesn't even bat an eyelash. He's tired of Basil, and after all, the artist hasn't painted anything really good for a while. Basically, Henry's totally unfazed by the idea that Basil might be dead in a gutter somewhere; he doesn't even really think that's a possibility, since, in his view, Basil's too dull to be murdered. That is way harsh.
But that's just how Lord Henry views life. People, money, objects, art – everything is just a tool of pleasure to him. Once any given thing stops being fun, he's not interested any more. The one possible exception to this is Dorian himself. After years of "developing" Dorian's personality, Lord Henry feels as though he's created the ideal human being. He admires Dorian profoundly, but more importantly, he admires himself for having made Dorian what he is.
All along, we see that Lord Henry and Dorian's friendship was nothing but a kind of science experiment; Lord Henry introduced a series of malicious elements to a pure subject, and watched their corruptive influence take hold. Since, in his mind, he molded Dorian in his own image, he doesn't think the other man can possibly ever change back. And that's Henry's ultimate malicious triumph – he has created his own perfect companion, who is his equal (or better) in every way. The only thing Lord Henry neglected to foresee was the fatal intervention of conscience…but that's probably because he doesn't have one.