That's the way it is!
Meanings
In situations where you aren't entirely thrilled with the status quo or the outcome of a situation, but have resigned yourself to accepting it for what it is
Examples
He's a careless person and he shouldn't have been promoted to supervisor. But, that's the way it is! 
È un irresponsabile e non avrebbe dovuto essere promosso a caporeparto, ma tant'è...After an argument with my boy-friend, I even refused to answer his telephone calls for days. Now I regret it, but that's the way it is!
Dopo aver litigato con il mio ragazzo, non ho risposto alle sue chiamate per giorni. Adesso me ne sono pentita, ma tant'è…