He should be worried too because his back is going to be sore tomorrow, as well as other parts of his body (he's sure Rachel will be suffering the same problem come tomorrow morning). But right now all he wants is for her to mark his skin, have her mark her territory on him and pretend like he's hers. Which he is. He might be dating Amy but a part of him will always belong to Rachel, and that part is his heart. The problem is that Rachel isn't his. But right now he can pretend.

He's dying to come so when he feels her go over the edge he's crying out in relief, only holding on for this long so they could let go together. He empties himself inside her with a firm jerk of his hips, and he does it plentifully, still moving as he rides out her orgasm and his own high but at a slower pace than before.