it just me or it feeling like the fight again the goddess not just ripped out his original power, but his emotions as well. leaving him with the remain emotion that his past never used (probably he's originally kind hearted MC like person), negative emotions. he clinging into what remains of him to keep his sanity. until his body decay from the curse.
Honestly? I don't think so - I'd say it's more of the case of him having fallen into despair, and gone insane from all that's happened to him. If you look at what's been said in the manga so far, Setsuna got betrayed by his lover for the god's power, lost the ability to even so much as cast regular magic, and can only use magic that hadn't been invented yet.
Like, I've gone on a small rant a few chapters ago about how broken he is, but since then I'd say the story has only made his supposed fall from grace that much more tragic.
In one chapter, although brief, you can see him mention that he has a body that "can't sleep", but if you take another look at his character design after that, one thing becomes apparent;
Setsuna has massive bags under his eyes, meaning that he's suffering from insomnia. Just because he has a body that's unable to sleep, doesn't mean the effects of sleep deprivation don't come with it. It's like another intentional curse placed upon him to ensure he stays in line and is unable to do much with himself on a regular day-to-day basis. The result of this is a man who went of the deep end with his lust and made an entire magic system around it, to the point where he can literally enchant, a FUCKING plastic zip lock bag, with never before done time-stasis magic. The levels of madness you have to reach for that is absolutely insane.
iirc from what I've seen as well in chapter 13 - Setsuna smokes a large cigar, very likely for the medicinal purpose of pain relief. Presumably, whatever form of indica weed or so exists in said universe.
All in all, it really makes you think. Especially this - when you see the Images of Ria - Setsuna's former vamp gf, look at her eyes; they also have bags under them. In some panels of the past it isn't quite that bad, but in the present, they're the same as Setsunas. Heavy bags under the eyes. She didn't have those in specific panels right before the fight with the gods and when she was still together with Setsuna.
meaning: Just like Setsuna, Ria was cursed, but presumably somewhat before the fight, and it's effects grew stronger over time till they reached a climax during the Magic Battle that happened. In essence, she's a victim of the gods overly amplifying her desire for power to the point that it actually became an obsession, with Setsuna unfortunately none the wiser.
If anything, she's just another play thing for the gods, her mind falling apart even more as time goes on, till she, too, inevitably decays.
It really makes you hate the gods of this world's universe, doesn't it?