Let's say you're the male in a relationship. Your spouse is nearing 40. She wants a child. You don't, but you don't want to lose her. What's the best course of action for you?
The best course is not to tell your spouse that you don't want a child. Rather, you want to act uncertain. Say you need more time to make up your mind. It's a tough decision, yadda, yadda. You should be able to keep up that act for a few years.
Maybe, on her 39th birthday, she'll tell you that you now need a definitive answer. It might be the best thing to do is to pretend that you've made up your mind and, yes, you want a child - only to have a steady flow of migraines coming your way.
At some point, the problem will have solved itself biologically.
One might say that such a course of action would be immoral. It is problematic indeed. But it is worth keeping in mind it only presents itself as attractive to the extent that men - who, after all, tend to know their spouses pretty well - think they have reasons to believe they'll be dumped if they don't agree to deliver the sperm.
Love, as Professor Benatar once put it, is a battlefield.