I agree with you
i dunno that i would necessarily classify this as stock.'s since the uke knew the seme was possessive and creepy but still stayed with him anyway. he even egged him on a couple times (telling him to eat him, telling him to masterbate in front of him, etc). if he really didn't want that kinda relationship then he had plenty of chances to distance himself from the seme. (this was all before he was confined btw)
normally i would agree with the stock.'s diagnosis but not in this case, because the uke didn't leave or even put some distance between them even after the seme's craziness was made blatantly obvious to the uke (before the chains and imprisonment).
I won't lie it was all good until the seme changed and the uke misplaced love for his Stockholm's Syndrome(〜￣△￣)〜