[ He's not sure if it's the frenzied thrusts or the sheer level of acceptance that she's baked into such a simple sentence that makes him break, but break he does. Harmony was fun but vapid and Dru may have adored him from time to time but it was never just him and her frail health coupled with her tendency to snog anything that moved left him feeling like he was constantly competing for her attention. She was never truly his, unlike him who had never been anything but fully hers.
But this. This. It's casual and fun and liberating. Even more so it really is the two of them against the world, no ifs, no buts, no justification or turning a blind eye or pretending that it's just delirium, just confusion, just some impulse from her insanity that drives her into the arms of other men or demons or god-knows-what. This is something that is his and theirs and Rebecca, newly turned as she is, wants everything he's got.
Maybe it is just a cry in the throes of passion but it hits him in just the right places and so he comes, hard and solid, grunt choked off in his throat and muscles trembling under his continuous efforts to draw it out, go a little further, make her proud and happy and satisfied. All he ever wanted. ]