SB 10.46.6

dhārayanty ati-kṛcchreṇa
 prāyaḥ prāṇān kathañcana
pratyāgamana-sandeśair
 ballavyo me mad-ātmikāḥ
Synonyms: 
dhārayanti — they hold on; ati-kṛcchreṇa — with great difficulty; prāyaḥ — barely; prāṇān — to their lives; kathañcana — somehow; prati-āgamana — of return; sandeśaiḥ — by the promises; ballavyaḥ — the cowherd women; me — My; mat-ātmikāḥ — who are fully dedicated to Me.
Translation: 
Simply because I have promised to return to them, My fully devoted cowherd girlfriends struggle to maintain their lives somehow or other.
Purport: 

According to Śrīla Viśvanātha Cakravartī, although the gopīs of Vṛndāvana were apparently married, their husbands actually had no contact whatsoever with their supremely attractive qualities of form, taste, fragrance, sound, touch and so on. Rather, their husbands merely presumed, “These are our wives.” In other words, by Lord Kṛṣṇa’s spiritual potency, the gopīs existed entirely for His pleasure, and Kṛṣṇa loved them in the mood of a paramour. In fact, the gopīs were manifestations of Kṛṣṇa’s internal nature, His supreme pleasure potency, and on the spiritual platform they attracted the Lord by their pure love.

Nanda Mahārāja and mother Yaśodā, Lord Kṛṣṇa’s parents in Vṛndāvana, had also attained a most exalted state of love for Kṛṣṇa, and they too could barely maintain their lives in His absence. Thus Uddhava would also give special attention to them.