At the time of his escape, Bucky had been near the end of the process of getting his dick broken. The conditioning hadn't gotten far enough to actually physically rewire him, so he can still come however he wants. But he'd had it pounded into him how he was supposed to get off -- and how they'd hurt him if he orgasmed outside acceptable parameters.

So what I'm looking for here is a thing where Bucky can fuck just fine, but as soon as he comes he's flooded with anxiety, guilt, and the hypervigilant subconscious expectation of punishment. This black-light afterglow can last for hours. The alternative is just fucking the (horrible/painful/humiliating) way Hydra wanted him to; at least he gets to avoid the panic attack afterward, if not the shame. Except he finds it awful to bring his trash to bed, and that feels like letting Hydra win.

+ at first Bucky has no problem enjoying sex, but gradually the dread of the emotional whiplash that always ensues ruins the fun for him

+ Bucky switches between fucking in compliance Hydra's training and against it, but both ways are pretty horrible for different reasons

+ a partner (preferably Steve, Sam also works) who is supportive but totally out of his depth, and eventually also emotionally strained

+ miseryyyyy