Perhaps Kirk had the right attitude to love. He'd always admired Kirk's ability not to get tied down, to just enjoy being free. Once upon a time, he'd had that too, but the whole complicated mess with Ianto had - well. Made things more complicated.
Much easier to lose himself in physical sensation with someone who wanted nothing more from than that. He worked his own hips up against Kirk's as he plunged once more into the kiss, and gasped sharply when he felt his cock taken in hand, squeezed against Kirk's own.
Breaking out of the kiss, mostly in order to breathe, he instead kissed his way across to Kirk's ear so he could murmur breathlessly into it, "Wanna switch things round and get fucked this morning? Or wanna take advantage of how lovely and loose you made me last night?"
Forgetting for a moment that Kirk didn't remember last night.