The “lusty attitude” of the gopis does not refer to any sort of sex indulgence. Srila Rupa Gosvami explains that this “lusty desire” refers to the devotee’s particular attitude of association with Kṛṣṇa. Every devotee in his perfectional stage has a spontaneous attraction to the Lord. This attraction is sometimes called the “lusty desire” of the devotee. The lust is the devotee’s excessive desire to serve the Lord in a particular capacity. Such desire may seem to be a desire for enjoying the Lord, but actually the endeavor is to serve the Lord in that capacity. For example, a devotee may desire to associate with the Personality of Godhead as His cowherd friend. He will want to serve the Lord by assisting Him in controlling the cows in the pasturing ground. This may appear to be a desire to enjoy the company of the Lord, but actually it is spontaneous love, serving Him by assisting in managing the transcendental cows. This extreme desire to serve the Lord is manifest in the transcendental land of Vraja. And it is specifically manifested amongst the gopis. The gopis’ love for Kṛṣṇa is so elevated that for our understanding it is sometimes explained as being “lusty desire.” The author of Sri Caitanya-caritamrta, Kaviraja Kṛṣṇadas, has explained the distinction between lusty desire and the service attitude in this statement: “Lusty desire refers to the desire to gratify one’s personal senses, and transcendental desire refers to the desire for serving the senses of the Lord.” In the material world there is no such thing as a lover wanting to please the senses of his beloved. Actually, in the material world, everyone wants mainly to gratify his own personal senses. The gopis, however, wanted nothing at all but to gratify the senses of the Lord, and there is no instance of this in the material world. Therefore the gopis’ ecstatic love for Kṛṣṇa is sometimes described by scholars as being like the “lusty desire” of the material world, but actually this should not be taken as a literal fact. It is simply a way of trying to understand the transcendental situation. Great devotees up to the standard of Uddhava are very dear friends of the Lord, and they desire to follow in the footsteps of the gopis. So the gopis’ love for Kṛṣṇa is certainly not material lusty desire.
Source : A.C. Bhaktivedanta Swami Prabhupada (2011 edition), “The Nector of Devotion”, Page 122 & 123