Just another thought- HOW much do you want children? Why do you want marriage? Is it the commitment factor- or the status or security?
If you can answer that, it might help you decide what to do.
I hate to say this, but your chances of getting pregnant at 40 are quite low anyway- yes, (I hear the chorus!!) many women do conceive at 40+, BUT statistically you are much less likely to.
There is no guarantee either that even if this man said "Yes" to all you want, that a baby would appear- he might be infertile, or you too. No partner comes with a 100% guarantee of their baby-producing power- though admittedly, not wanting them is rather a hindrance.
How much do you want HIM? Are you wanting a partner, or a baby? Yes, I know you will say "Both", but if you only had to choose 1, which would it be?
What if you met Mr Right and he knew he was infertile? Would you leave him?
I have heard the argument he puts forward many time "Too many of my friends are divorced" etc etc- imo, this is a cop-out. men often say this, then 6 months later they have a whirlwind romance and whoosh- down the aisle they go. Maybe it's just you and him who aren't "right"?
I believe- maybe naively- that if a man really loves a woman and feels he will lose her, he will marry her, if being married is what she really wants.
I still stick with my previous post- emotionally, you have to accept he may never give you what you are asking for- but until you make the break, you will never be able to test his feelings for you.