Now, getting down to the questions you asked in your letter to me. First, Is it a good thing to have sexual relations?
Certainly - but only within a certain context. It's good for a man to have a wife, and for a woman to have a husband. Sexual drives are strong, but marriage is strong enough to contain them and provide for a balanced and fulfilling sexual life in a world of sexual disorder.
The marriage bed must be a place of mutuality - the husband seeking to satisfy his wife, the wife seeking to satisfy her husband.
Marriage is not a place to "stand up for your rights." Marriage is a decision to serve the other, whether in bed or out.
Abstaining from sex is permissible for a period of time if you both agree to it, and if it's for the purposes of prayer and fasting - but only for such times. Then come back together again. Satan has an ingenious way of tempting us when we least expect it.
I'm not, understand, commanding these periods of abstinence - only providing my best counsel if you should choose them.
Sometimes I wish everyone were single like me - a simpler life in many ways! But celibacy is not for everyone any more than marriage is. God gives the gift of the single life to some, the gift of the married life to others.