I'll leave it up to others to gauge him, but as far as her having a hard time(so to speak), look at her face and listen to her at the beginning, like nothing. Later she is then not having a hard time, either, but expression about her own bizness.
How about she keeps her knees together or places her hand so the dick goes between her fingers to make it an inch (or more) less, then she sounds like it is difficult somehow as the cock goes in bit by bit? Then they argue over who squirted on the sheets. It was her.