I think that in this novel we can see Kerouac struggling to come to grips with his own failings, and struggling to find a place for himself in a world he doesn't understand.

It is clear that Kerouac, at this point in his life, feels like a failure, as he watches his friends' successes throughout the novel.

Loneliness is definitely a theme of this novel; it carries over from Part One and is an undertone through the whole thing.

Desolation Angel's definitely shows how Kerouac looked at himself at that time in his life, though throughout the novel the reader has a sense that he is firm and steady with his beliefs and although he's on a different path than his friend, the path he's on is the right path for himself. I don't think Jack Kerouac would've been truly happy/happier if he was on the same path as his friends.