Daniel isn't sure what to do with himself. He thinks he wants to get a hobo outfit and a sign that says "what now, universe?" He feels as though the universe is an asshole and isn't paying attention, just like Charlie. As Daniel thinks about how Charlie ruined his chances with Natasha, he thinks of how much he hates him. He thinks that he's wanted to punch Charlie for years now, and now he has nothing left to lose.
It's worth recognizing that Daniel doesn't find the courage to confront Charlie until he decides that destiny doesn't actually exist, which suggests that Natasha isn't entirely wrong: for Daniel, there is newfound freedom in believing that he can cause things to happen with his own actions.