Originally Posted by snowy

I'm not a doctor (obviously) but it sounds like it could be vaginismus.

You really need to get her to a doctor to rule anything out. Even a GP will do, really--it's best to start there and the GP can point you in the right direction, if need be.

Originally Posted by amonkie

couple things.

The vagina was not made for things to be forced like a cinderblock.

What are you doing in terms of foreplay? Are you using lube? Foreplay is not just 10 minutes of heavy kissing and petting, it is getting both of you aroused so that her body is helping you. Girls getting wet isn't just a "omg that is so cool" thing, it is the body's natural lubricant that helps make penetration easier.

There have been days where putting in a tampon felt like there was barely going to be enough room, and then other days where I've had sex and obviously a penis is significantly larger than a tampon and it fit with no problem. The difference between the 2 scenarios is that the natural lubricant and body response made things vastly easier.

I really can't offer any further advice or questions until we know about this, since it is a pretty big part of successful sex and I did not see it mentioned at all in your post.