All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
This divorce that is imposed by the court could be either revocable or irrevocable. If irrevocable, then this man having sexual intercourse with this woman is, in this case, considered as having intercourse with someone to whom he is not married. Likewise, if the divorce is an irrevocable divorce with minor separation, then he has no Raj‘ah [returning to a full state of marriage] to her except with a new contract (of marriage), and if it is an irrevocable divorce with major separation, she is not lawful to him until she marries another husband and he divorces her or dies. Further, if the wife is separated from her husband and her ‘Iddah expires, then she is allowed to marry someone else.
In the case that the divorce was revocable, then the Raj‘ah can occur in different ways which include sex or foreplay according to the opinion of Hanafi scholars, as clarified in Fatwa 89845. They also mentioned that this Raj‘ah is valid in all cases. The Hanafi scholar Al-Kaasaani said in Badaa’i’ As-Sanaa’i’: "Likewise, it is not a condition of Raj‘ah that the husband be compliant, serious, or intent. Rather, this return is valid even under compulsion, by way of joking and playing, or merely by mistake. This is because this Raj‘ah is the preserving of a marriage." He also said: "The same applies even if she has sex with him while he is asleep or in a state of insanity."
If the Raj‘ah occurs, the bond of marriage resumes, so she is not allowed to marry someone else.
Finally, we draw your attention to the fact that the divorce issued by an Islamic judge is irrevocable except in some cases, like when it is without Eelaa’ (a husband swearing not to have sexual intercourse with his wife and refusing to approach her) or due to financial insolvency, as the scholars have clarified.
Allaah Knows best.