CC Ādi 4.195

ataeva sei sukha kṛṣṇa-sukha poṣe
ei hetu gopī-preme nāhi kāma-doṣe
Synonyms: 
ataeva — therefore; sei — that; sukha — happiness; kṛṣṇa-sukha — the happiness of Lord Kṛṣṇa; poṣe — nourishes; ei — this; hetu — reason; gopī-preme — in the love of the gopīs; nāhi — there is not; kāma-doṣe — the fault of lust.
Translation: 
Therefore we find that the joy of the gopīs nourishes the joy of Lord Kṛṣṇa. For that reason the fault of lust is not present in their love.
Purport: 

By looking at the beautiful gopīs Kṛṣṇa becomes enlivened, and this enlivens the gopīs, whose youthful faces and bodies blossom. This competition of increasing beauty between the gopīs and Kṛṣṇa, which is without limitations, is so delicate that sometimes mundane moralists mistake these dealings to be purely amorous. But these affairs are not at all mundane, because the gopīs’ intense desire to satisfy Kṛṣṇa surcharges the entire scene with pure love of Godhead, with not a spot of sexual indulgence.