Unfortunately most people aren't really motivated to fight for the sake of fighting, they're usually motivated because there's some sort of incentive involved. In a situation where it is just War for the sake of the War, but it's also a War that no one seems to be making any actual progress on, it's not surprising that discontent with the status quo is going to increase without either financial or material incentives to keep going. 

Or because they've been brainwashed, but you already nixed that idea.