If it hasn't happened for you by 21, then it's probably not for you, ever.
It seems to be a pretty real standard of judging whether or not someone is weird IRL.
You don't see many normal 30 year old virgins, frankly. We're all on this planet to poop out the next generation. If you don't do that (for whatever reason) you're a failure by nature's standards.
I think it may not be good to call people failures for not wanting to do a thing that we with our current understanding of it think is intended by nature, especially as if that understanding changes a lot or completely in the future, that would just make it worse,
But you can choose what you want to do, personally I think that the purpose of life is to live, and I think that's true whether you look at religion, where God in major religions is a spirit of life or creates life just to have people exist and continue to live, or whether you look at people's current understanding of science, where, if it's true that your biological purpose is to have kids, that means not only is your body's biological purpose to live and to continue life, but also that, just as the next generation would be our bodies' biological goal, we were also at one point the goal of nature,
So the point of life is to live, not to have intercourse or to do something else,
And if I may include something specific to christianity, I think that the idea that the purpose of life is to worship God shows this too, why? Because in christianity God is called life, so if you worship God, you follow God, you follow life, you live, the point of life is to worship God, God is life, the point of life is to live,
John 14:6 - Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.