What is the ruling on the chatting between a young man and his girlfriend?

Private chatting between the two sexes entails religious violations, and leads to prohibited attachment.

What is the ruling on the mother who resorts to practitioners of witchcraft to make her son hate his wife?

All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

What she is doing is forbidden and amongst the seven destructive sins. Hence, she must make repentance, seek forgiveness from Allah, regret what she has done and adhere to the teachings of Sharia. And Allah The Almighty Knows Best..

Is it permissible for a woman to adorn herself with kohl (eyeliner) and go out wearing it?

Kohl is a form of adornment, and it is forbidden for a woman to display her adornment to anyone other than her husband or a Mahram. And Allah Knows Best.

Is it permissible for a Muslim physician to specialize in gynecology obstetrics, and what is the ruling on working as such?

Some fields of knowledge are an individual duty while others are a collective one, and specializing in gynecology obstetrics is a collective duty. However, if there were female physicians to treat women, then there is no need for a male gynecology obstetrics specialist to look at women`s Awrahs (private parts) except in necessary situations since the jurisprudential maxim says:” Necessity must only be assessed and answered proportionately.” And Allah Knows Best.