My boyfriend and I have messed around for quite awhile now[just grinding, dry humping, anal, etc. No vaginal sex] and we feel completely comfortable with each other. However, recently we started trying to have sex and when we did he said it was as if the hole was too small. I got a mirror and checked and the hole was completely covered and things down there had tightened up a bit from what I could tell. After getting unaroused again, I checked once more and it was as it should be. Yesterday for the first time, he was actually able to get a finger inside during anal sex. It felt a bit uncomfortable but it didn't hurt and it felt pretty good. We stopped anal and switched to 'missionary' so he could try again, but he said it looked closed off and like it was just a wall of flesh. He moved his finger around a bit and was able to find the hole, but he said it seemed as if a bone was in the way and he had to go under it to get to the canal. And when he tried sticking a finger inside, it hurt a lot, though he was able to get inside a bit.

If anyone could explain what they think it is or whatnot, It'd be much appreciated.