How to overcome extreme pain during sex?

Hello doctor,

I am 24 years old, and my boyfriend is 25 years old. We have been in a relationship for the last four years. We never got physically intimate and never had penetrative sex. Now but whenever we try or make an attempt towards penetrative sex or intercourse, I push him away as it hurts me a lot with an immense height of pain. My vaginal muscle seems to become tight. Also for then for him, it becomes very difficult for him to insert his penis into my vaginal. Is there any way to start the sex between us, and is there any way to make it less painful or any way where it will not be? Because as soon as it hurts, my mind and concentration instantly go toward the pain, and I cannot continue with the intimacy. Please suggest a solution for this. Soon we are planning to get married. This will help us with future planning too.

Thank you.