BBC programme about Medieval lives discussed this.
http://www.bbc.co.uk/programmes/b03d6c64Unlike birth and death, which are inescapable facts of life, marriage is rite of passage made by choice and in the Middle Ages it wasn't just a choice made by bride and groom - they were often the last pieces in a puzzle, put together by their parents, with help from their family and friends, according to rules laid down by the Church.
Helen Castor reveals how in the Middle Ages marriage was actually much easier to get into than today - you could get married in a pub or even a hedgerow simply by exchanging words of consent - but from the 12th century onwards the Catholic Church tried to control this conjugal free-for-all. For the Church marriage was a way to contain the troubling issue of sex, but, as the film reveals, it was not easy to impose rules on the most unpredictable human emotions of love and lust.
Why does there seem to be a very wide spread acceptance of arranged marriages? Has it not been a contract between consenting parties? Are women and men not even equal in marriage? Programmed discusses "the marriage debt". Is there an equivalent idea in Islam?
Is it a mortal sin to refuse one’s husband or wife the marital debt?
Conjugal relations are rightly called the "marriage debt", which each spouse owes the other in justice the relations that are apt to engender children. It is this very particular right over one’s body that is given up to one’s spouse by marriage vows. Saint Paul is very explicit about this:
Let the husband render the debt to his wife, and the wife also in like manner to the husband. The wife hath not power of her own body, but the husband. And in like manner the husband also hath not power of his own body, but the wife. (I Cor. 7:3 & 4)
A debt in justice obliges under pain when a serious matter or quantity is owed. However, marriage relationships are a serious matter and of great importance. Furthermore, the refusal of the marriage debt may cause a danger of incontinence.Consequently, it is a mortal sin to deprive one’s spouse of these relationships. The typical example of this is when a wife feels that she is justified in withholding the marriage debt because her feelings are hurt, or she is not appreciated enough. However, there is no excuse for the husband to withhold the affection and care for his wife’s feelings, for is responsible for them as head of the family.
However, it is possible for the couple to agree, by mutual consent, to abstain for a short period of time, for example for penance, during Lent. However, it must be by mutual consent, and on the understanding that either spouse can withdraw it at any time. Saint Paul speaks of this also:
Defraud not one another, except, perhaps, by consent, for a time, that you may give yourselves to prayer (I Cor 7:5).
There can, however, be good reasons that excuse a husband or wife from rendering this marriage debt, such as adultery of the other spouse, or unreasonable demands (e.g. frequency, intoxication) or grave danger to health or life (e.g. by the possible communication of infectious diseases), or a husband who refuses to perform his duty of supporting his family (Jone, Moral Theology, pp. 557 & 558). There can also be special circumstances that reduce the culpability of refusing the marriage debt, so that it is only a venial sin, for example "if the petitioner will readily renounce his right, or if rendering it is only briefly postponed, or when the use of the marriage right is frequent and its refusal is only rare" (ibid). [Answered by Fr. Peter R. Scott]
http://catholicforum.fisheaters.com/index.php/topic,3453185.0.html