If a married woman who is not happy with her husband love other man or make relation with him. In that case she will divorce?

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 is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

A woman is not divorced by loving or establishing a relationship with a man other than her husband. She will not be divorced until her husband divorces her.

Nonetheless, you have to know that it is forbidden in Islamic Law for a woman to establish a relationship with a marriageable man, and this matter is even more forbidden and more serious if the woman is married. A woman, who has a relationship with a man other than her husband, is very sinful, and it is not safe that she will not have children from this second man. So she has to repent and cut the relationship with this man immediately and she should know that she will stand in front of Allaah in a Day that is 50,000 years long. So she has to prepare an answer for her abominable sin.

Allaah Knows best.