It's possible to play the 'Open to Children' card for a very long time, especially if the woman in the interaction isn't prioritizing having children.
Take a look at the blog post below. 70% of relationships end within 12 months. I think that covers both the casual sex interactions (which usually burn out in less than 12 months) and exclusive monogamous relationships. It's possible that the child issue doesn't come up at all before the relationship fails, even if I am operating in a monogamous frame with a woman.
How long does the average relationship last? In this article, you'll lean about average relationship length by age, before marriage, and...
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My position is 'Open to Children but not prioritizing it'. That seems to work well enough for me. My stance on children hasn't been the primary cause of breakups. The majority of the women I've had sex were using birth control. I have also had women tell me that they didn't want children when I stated what my position was. I never outright say "I don't want children". That position helps with attraction and seduction. I do not wish to shrink my dating pool and I don't have to do that.
It is true that I have promoted the idea that relationships have a shelf life of 3-5 years. I am open to staying beyond that 5 year point. I don't like the idea of staying too long in a relationship and experiencing the worst decay.
A lot of relationships that make it to 2 years fail between Year 2 and Year 5.
Relationships that go beyond 5 years are in a state of significant decay in a lot of cases.