prauḍha - matured; nirmala-bhāva - pure condition; prema - love; sarva-uttama - best of all; kṛṣṇera - of Lord Kṛṣṇa; mādhurya-rasa - of the mellow of the conjugal relationship; āsvāda - of the tasting; kāraṇa - the cause.

Her pure, mature love surpasses that of all others. Her love is the cause of Lord Kṛṣṇa’s tasting the sweetness of the conjugal relationship.