Remus accepted the kiss gladly, and before Severus' hand could slip entirely out of his hand, Remus gave it a little squeeze and smiled. He was frankly amazed Severus had lasted this long and had been so ... agreeable towards Harry. Perhaps the scheming had kept his mind occupied, but now that it was over it was no surprise Severus would want to leave, probably and preferably before he lost his patience with either of them.
Then he turned towards Harry "Severus is right. It'll be a bit hard, but better a swift pain while you're perhaps distracted by other matters, than a long drawn-out ache." Remus smiled reassuringly at Harry.