They ask thee concerning women's courses. Say: They are a hurt and a pollution: So keep away from women in their courses, and do not approach them until they are clean. But when they have purified themselves, ye may approach them in any manner, time, or place ordained for you by Allah. For Allah loves those who turn to Him constantly and He loves those who keep themselves pure and clean. (Quran 2:222)

Inhabitants of Medina gathered together from different places bringing different customs which were related to marriage, divorce and relation between family members. Islam regulated these customs under one law which matches with the teachings of modern sciences and regulations of modern societies. Also, there is no taboo in Islam. Quran discloses even the most intimate subjects what can occur between man and woman. The next ayas are instructions for establishing healthy family and social life. Therefore, basic principles had to be clarified for all members of Umma:

• Women’s course or menstruation is not a disease. It serves for purifying women.
• Sexual act is like tilling the soil and seeding. It is acceptable if the aim of sex is procreation offspring or seeking each other’s pleasure by allowed way. Oral or anal sex where not the “tilth” and “fertile soil” is the objective is prohibited.

Your wives are as a tilth unto you; so, approach your tilth when or how ye will; but do some good act for your souls beforehand; and fear Allah. And know that ye are to meet Him (in the Hereafter), and give (these) good tidings to those who believe. (Quran 2:223)

In the previous aya, the Quran uses the word "tahara" three times explaining purification. This word expresses not only physical but also spiritual purification and "making ourselves purified for doing a sacred deed". In a later Surah the same kind of spiritual purification is mentioned in regard with Jesus, also using the word "tahara"

Behold! Allah said: "O Jesus! I will take thee and raise thee to Myself and clear thee (of the falsehoods) of those who blaspheme; I will make those who follow thee superior to those who reject faith, to the Day of Resurrection: Then shall ye all return unto me, and I will judge between you of the matters wherein ye dispute. (Quran 3:55)

In this way, Allah elevates legal sex from the world of instincts. With the word “tahara”, the intercourse between husband and wife is a sanctity and becomes an act of faith. This also implies that such an act can only be done with the will of both parties. Violence is excluded.

What does separation mean during menstruation? Moving to another room? No! Here you are the answer:

Narrated Zainab bint Abi Salama:

Um-Salama said, "I got my menses while I was lying with the Prophet under a woolen sheet. So, I slipped away, took the clothes for menses and put them on. Allah's Apostle (peace be upon him) said, 'Have you got your menses?' I replied, 'Yes.' Then he called me and took me with him under the woolen sheet." Um Salama further said, "The Prophet used to kiss me while he was fasting. The Prophet and I used to take the bath of Janaba from a single pot."

Classification: Authentic
Sahih al-Bukhari, Book of Menstrual Periods, Hadith 319

Prayer cannot be performed only during menstruation. In case of non-menstrual bleeding, all religious duties can be fulfilled:

Narrated 'Aisha:

Fatima bint Abi Hubaish said to Allah's Apostle, "O Allah's Apostle! I do not become clean (from bleeding). Shall I give up my prayers?" Allah's Apostle replied: "No, because it is from a blood vessel and not the menses. So, when the real menses begins give up your prayers and when it (the period) has finished wash the blood off your body (take a bath) and offer your prayers."

Classification: Authentic
Sahih al-Bukhari, Book of Menstrual Periods, Hadith 303