He formed a relationship with a girl who is married and he wants her to get divorced so that he can marry her

No File Exists
Check below answers in case you are looking for other related questions:
Married to a man who neglects the prayer: what should she do?
He had an argument with his wife and got to know a girl over the phone

No File Exists
Related Answers:
Ruling on a woman being alone in a room with an officer so that she may get what she is entitled to
Should she continue her studies in a mixed school where there are no Muslims?
Is it permissible to study in a mixed educational centre with better qualified teachers, when there is another centre where there is no mixing but the teachers are less qualified?
Married to a man who neglects the prayer: what should she do?
He had an argument with his wife and got to know a girl over the phone

Recommended answers for you:
Celebrating the night of the Isra’ and Mi’raaj
Woman’s ‘awrah in front of other women and mahrams
Qaseedat al-Burdah by al-Busayri and an explanation of what it contains of kufr and heresy
Verses and hadeeth about hijab
Ruling on a person touching the Qur’aan without wudoo’, and the meaning of the hadeeth, “The believer is never impure”