Or also, I didn't think to mention, some gel or lubricant made for this purpose.
The mind has to be into it and if it is not, sex can be painful. I would get checked out and make sure everything is in working order first, and then reflect on the relationship to figure out why it is that you are not into it. Maybe you need more foreplay?
Have you seen a doctor about this pain? Normal, gentle sex shouldn't hurt. There's something wrong here, and a doctor could probably help.
If you are hurting, it is hard to get stimulated for sex. Once penetration happens, it is less painful and he can finish and enjoy himself, but in order to get yourself to the point where you are enthused about it, you might need some other ways. I would suggest you try drinking a little wine to see if that relaxes you, and maybe use lidocaine in the lower area so you know it won't hurt you. Read sex manuals, try things by yourself, and see if you can understand your body and what it likes.