CC Ādi 4.218

kṛṣṇera vallabhā rādhā kṛṣṇa-prāṇa-dhana
tāṅhā vinu sukha-hetu nahe gopī-gaṇa
Synonyms: 
kṛṣṇera — of Lord Kṛṣṇa; vallabhā — beloved; rādhā — Śrīmatī Rādhārāṇī; kṛṣṇa-prāṇa-dhana — the wealth of the life of Lord Kṛṣṇa; tāṅhā — Her; vinu — without; sukha-hetu — cause of happiness; nahe — are not; gopī-gaṇa — the gopīs.
Translation: 
Rādhā is the beloved consort of Kṛṣṇa, and She is the wealth of His life. Without Her, the gopīs cannot give Him pleasure.