Because views change as we get older. All my life I was certain I wanted kids, but now I’m doubting and maybe in a couple of years it will be a definite “no.”

For example, OP’s boyfriend could develop a successful carrier and then decide having kids doesn’t go with that.

Also, many relationships turn when the couple have kids. If OP and her boyfriend stay together despite their strong viewpoints regarding kids, that means at least now they’re favoring the relationship.

I’d say it also depends on the age. If you’re a guy in your 30’s, you’ll most likely will have figured if you want kids (usually a long before that), so then it’s easier to make the choice to breakup if the partner doesn’t want kids, when you do