Begging like that will definitely get her what she wants from him - she's difficult for him to resist at any normal time, so when she moans and shifts her body against his in such a manner, it becomes damn near impossible.

"Gladly, my love." He nips again at her neck and increases his tempo, working both of them towards another round of release. "Feels so good, you around me like this," he groans softly against her skin, his own words faltering and falling a bit out of order as his voice wavers. "Very lucky, your king is."

Even with the benefit of the spell to help with his stamina, he cannot last indefinitely moving in the way they are, his body in time and in tune with hers - and as much as he'd prefer to make her come for him first, sometimes it is just not possible to hold off, as it is in this case - his climax gripping hold of him slightly unexpectedly, as he cries her name loudly at the ceiling, erasing those earlier echoes.