First of all let me clear that Krishna was never lustful. In SriKrishna Ashtottarashatanama he is called as Anaadi Brahmachari which means “he is in ever brahmacharya”. He doesn’t possess materialistic qualities like lust. Remember one thing. Krishna doesn’t need anyone for his happiness. He is happy within himself. He is anandaparipoorna and swaramana. He doesn’t even needs Lakshmi devi for his ananda. That’s Krishna’s love for Lakshmi devi. Krishna never marries anyone except Lakshmi devi. Either it should be Lakshmi devi or Lakshmi sannidhana, then only Krishna will marry them. Otherwise, except Lakshmi, Krishna will not even touch any parastree.
Like how Lakshmi devi is Pativrataa in the same way Krishna or Lord Vishnu is Patnivrata. Thats why everything he accepts only when Lakshmi devi gives him. During Krishnavatara, SriRukmini devi and SriSatyabhama devi were saakshaat Mahalakshmi avatara (Sridevi and Bhudevi). Rest wives like Jambavati, Mitravrunda, Lakshana, Bhadra, Kalindi, Neela, Nagnajeeti etc. had the sannidhana or special presence of Lakshmi devi in them. Out of these queens Jambavati had the very special presence of Lakshmi devi in her.
Coming to the 16,000 queens, there are two reasons why Krishna married them:
1. These queens were kidnapped by Narakasura and were kept as prisoners in his kingdom. After Krishna killed Narakasura and crowned his son Bhagadatta as the king of Pragjyotishapura (now in Assam), he released all the 16,000 princesses. Now, no one would marry them because they stayed in Narakasura’s kingdom. Therefore, in order to save them from this insult, Krishna married them.
2. This reason is the most important reason. I have heard many people saying that if this was the case then was it neccessary for Krishna to marry them? He could have treated them as sisters too. But that wasn’t the case. SriMadhwacharya reveals it. These 16000 princesses were the sons of agnideva. They had done penance to please Brahma. Brahma pleased by the devotion appeared infront of them and asked what they wanted as boon. They asked Brahma to bless them with stree janma so that they can marry Krishna. At this Brahmaji said, “So be it.” All this Agniputras were born as princesses. Now as Krishna released them, Lakshmi devi entered each of them and they had the presence of Lakshmi devi in them and hence Krishna married them.
Now, coming to Srimati Radharani ji. She is the wife of SriKrishna Paramatma. Krishna in Vrindavana married the Gopikas who did Katyayani Vrata to get Krishna as their husband. The Gopikas’ relationship with Krishna is spiritual, devotional, and transcendental, not worldly or lustful. The Gopikas too had Lakshmi sannidhana in them, thats why Krishna married them. The “marriage” with the Gopikas is understood as spiritual union, reflecting their Lakshmi sannidhana and Krishna’s eternal nature. So, as per me, Srimati Radharani is the head of all the Gopikas. So, if Krishna married the unmarried Gopikas then its obvious he married Srimati Radharani. Srimati Radharani is best among the devotees of Lord SriKrishna in Vrindavana. So, there is no chance of Krishna leaving Srimati Radharani. Thats why he is also known as Radharaman laalju and Radhavallabh lalju in Vrindavana. At last SriKrishna gave moksha to all the Gopikas.
Now coming to Krishna’s sons, he had 10 sons from each of his wives. All these sons were devatas who by their will and by Krishna’s grace incarnated as Krishna’s sons. For example, Pradyumna is the son of Krishna and Rukmini devi and is the incarnation of Kaamadeva. Charudeshna was another son of Rukmini devi and Krishna who was the incarnation of Lord Ganesha. Like this all the sons were devata amshas.
So, in a nutshell, Krishna is not lustful. He marries only Lakshmi devi or Lakshmi sannidhana. The Gopikas of Vrindavana led by Srimati Radharani, other six queens led by Jambavati and other 16,000 queens had Lakshmi sannidhana in them thats why Krishna married them. Rukmini and Satyabhama were saakshat Lakshmi avataras.
Hope this helps!
Jay SriRam!
ShriKrishnarpanamastu!