What is the theme in Notes from the Underground by Fyodor Dostoevsky?

The need for companionship is a theme in the story. The author is continually seeking out companionship though he's never happy with the time he spends with another. He talks about his periods of dreaming, saying that he could never hold up to them for more than about three months at a time. It seems that he knows he's happier spending his time in solitude with only his dreaming, but somehow can't resist the need to seek out human companions. He says that he would find time to play card games and spend time with others but would inevitably find it unsuitable to continue spending time with them. Though he doesn't describe the partings, it seems likely that he would have parted with them as he did his former classmates, Simonov Zverkov, Trudolyubov, and Ferfichkin.