Does touching women temporarily forbidden in marriage nullify ablution?
It is prohibited to touch, or to shake hands with such women as they are considered strangers, and doing so nullifies ablution.
Is it permissible for one to masturbate in order not to commit fornication?
This is called committing the milder of the two evils such as eating a carcass in fear of death, and this happens when committing fornication is very likely to occur.
What is the Islamic ruling when parents oblige their son or daughter to divorce or marry, and this actually takes place, although it is against their will?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon Prophet Mohammad and upon all his family and companions.
When the husband utters the word of divorce, without being forced or threatened, divorce takes place and we recommend that you visit the General Iftaa` Dept. to be given the suitable advice in this regard. And Allah The Almighty Knows Best.
Does Husband fasting while being impure for having sexual intercourse with his wife at night permissible?
Yes it is permissible for you to fast because impurity isn't among valid fasting conditions, but you are obliged to perform ritual impurity in order to catch up Fajr prayer at its due time. And Allah Knows Best.