Although Daniel is a fanatical zealot, dedicated to the cause of throwing the Romans out of Israel, he doesn't much care for the lifestyle that his political activities necessitate. In order to avoid being captured by the Romans, Daniel and the other zealots must hide out in the mountains, far from their homes and the people they grew up with.
Some zealots deal with this situation better than others. But Daniel always feels incredibly lonely and isolated up in the mountains, even when surrounded by his comrades. This is because he feels much more keenly than the others the loss of friendship and true companionship.
Being a zealot may give Daniel a sense of belonging that comes from striving with others for a common purpose. But that sense, no matter how powerful, simply cannot replace the close bonds that Daniel has developed with Malthace and Joel in the village. That's because those bonds are based on common humanity rather than a shared political commitment or ideology.
It's no wonder, then, that when Daniel leaves the village behind to head back up to the mountains, he feels bereft over what he's left behind: the loving care that he will never receive from his comrades-in-arms.