aw Gunwook's perfect for chastity, he's a good good very good well-disciplined boy, he has great self control. I can see this being Gunwook's idea rather than Matthew's, because he wanted to push himself to see how much he can take. he'll use any excuse to prove what a good and talented, obedient boy he is. so good,,,,,,

but, even though he'd want to be denied, he's not above whining and begging and trying to guilt trip Matthew into unlocking him just to be a little shit. and Matt would have a hard time not giving in to his sad puppy eyes, he's too easily swayed. he couldn't handle torturing his baby for too long (and he's impatient too) so as a compromise, Gunwook is allowed to hump Matthew's leg, painfully hard in the cage, aching for the skin-to-skin contact he can't get.

when he's finally freed, Matthew takes pity and they bonk like crazy to work through Gunwook's withdrawals induced heat. poor puppy, he had to fight so hard against his instincts, Matthew's not gonna have his hands or holes empty for a while. but like you said anon, he earned this for enduring so well ♡