What is required from someone who abandoned the Ifadah circumambulation, believing that the first circumambulation sufficed for it?

Tawaf Al-Ifadah is a pillar of Hajj; Hajj is not complete without it. Therefore, whoever misses it has not completed their Hajj and must return to perform it. It is not permissible for a man to enjoy his wife as long as he has not performed Tawaf Al-Ifadah, because he has not yet completed the second stage of tahallul (exiting the state of ihram), which is only completed after Tawaf Al-Ifadah and Sa'i for those who are performing Hajj Tamattu' or Qiran, or for a Mufrid who did not perform Sa'i with Tawaf Al-Qudum.