Let's we don't establish a specific timeframe (but rather expect you to realize we want a family one day) and never nag you at all, have so much patience, let you take all your sweet time, given that you aren't going to waste our entire fertile years... ok then.
If it was up to you as a man (I'm sure you about our physical biology too), how long would you keep us as your childless girlfriend? For many many years would you keep us into the ''Oh we're having a great time, I like how things are now, oh the great sex'' honeymoon period without any real commitment?
Or would you eventually want a family too even if the woman doesn't nag nor establish a specific timeframe?