My ex and I were both virgins -- the first for each of us! Compared with later times, the first was definitely slower to get in what length I did, which wasn't the total length of my cock. After the first few times, there were no problems with ramming in as much as I wanted. The few times she had a problem necessitated some repositioning before continuing. But, then, my penis is not the monster that some of you have, it's just a hefty above average.
