Lord Krishna has many wifes excluding Radha or Rukumini (i assume both are same), this question says about what happens to Radha after Lord Krishna. but What happened to other wives of Lord Krishna after he left?
Only very few scholars think that Radha and Rukmani are same. Most of the scriptures say that they were different.
What happened to Rukmiṇī and other major wives of lord Krishna after he left?
rāma-patnyaś ca tad-deham
pradyumnādīn hareḥ snuṣāḥ
kṛṣṇa-patnyo ’viśann agniṁ
The wives of Lord Balarāma also entered the fire and embraced His body, and Vasudeva’s wives entered his fire and embraced his body. The daughters-in-law of Lord Hari entered the funeral fires of their respective husbands, headed by Pradyumna. And Rukmiṇī and the other wives of Lord Kṛṣṇa — whose hearts were completely absorbed in Him — entered His fire.
Other survivors of the Yadu dynasty — the women, children and old men
Arjuna took the survivors of the Yadu dynasty — the women, children and old men — to Indraprastha. He installed Vajra (the son of Aniruddha) as ruler of the Yadus.
Related chapter of Śrīmad-Bhāgavatam (Bhāgavata Purāṇa) : SB 11.31: The Disappearance of Lord Śrī Kṛṣṇa
https://www.sacred-texts.com/hin/m18/m18005.htm Swargarohana Parva Section V
16,000 women had been married to Vasudeva as his wives. When the time came, O Janamejaya, they, plunged into the Sarasvati. Casting off their (human) bodies there, they re-ascended to Heaven. Transformed into Apsaras, they approached the presence of Vasudeva.
Those 16,000 wives of Krishna were originally Apsaras born on earth as stated in Adi Parva, Section 67.
And, O king, the portions of the tribe of Apsaras which I have mentioned already, also became incarnate on earth according to Indra's commands--And sixteen thousand portions of those goddesses became, O king, in this world of men, the wives of Vasudeva.
Krishna also had other wives such as Rukmini and Satyabhama.
In Mausala Parva, Section 7 describes what happened to them
Rukmini, the princess of Gandhara, Saivya, Haimavati, and queen Jambavati ascended the funeral pyre. Satyabhama and other dear wives of Krishna entered the woods, O king, resolved to set themselves to the practice of penances. They began to live on fruits and roots and pass their time in the contemplation of Hari. Going beyond the Himavat, they took up their abode in a place called Kalpa.