And what about those married who cannot have children or who are beyond childbearing?
What about it? What point are you trying to make?
Man's fertility is not a poison. Woman's fertility is not a disease. Contraception and voluntary sterilization (partial mutilation of the sexual organs) treat a properly functioning human body as either poisonous or diseased.
There's no problem with sexual intercourse at a naturally infertile time or with a naturally infertile spouse. Most of the time, for most people, sex does not result in pregnancy most of the time, and that's just the way God made it. OK by Him, OK by me.
The trouble is with intentionally disabling or sabotaging fertility. That shows a will that is actively and destructively directed against something which is good in itself.
It's in some respects to be compared with eating. There's nothing against enjoying the pleasure of eating, whether or not it's the "very most nutritious possible." But bulimia --- repeat binge-eating-and-throwing-up --- is unnatural and unhealthy, and if intentional, wrong.