The husband, because he maintains the wife, is called Bharta, and he is called Pati, because he protects her. When he fails to discharge these two functions, he ceases to both Bhartri and Pati.
भरणाद्धि स्त्रियो भर्ता पालनाद्धि पतिस्तथा। गुणस्यास्य निवृत्तौ तु न भर्ता न पुनः पतिः॥