
He's not fking around. There's very awful reason why Nanmu had to sleep with those two, old man (forgot his name) literally made him endure all if that as punishment (he's literally been raped all this time). And despite loving someone people still can have sex with others. Pilgyun left, Nanmu isn't in the best place mentally and emotionally and the guy he slept with loves him. It's the only place he thought he could seek warmth and acceptance at the moment. But despite of it he felt guilty. Which is nothing like just sleeping around. He's just lost.

Absolutely. It's all because of that fucking old meddling looking bastard who couldn't understand that Pil-gyun's bio mom didn't love his stinky old ass.
The whole sex thing was probably a trauma response. Nanmu was raped endlessly and the only comfort he had was the choice he made to let his "brothers" do that to him instead. So when pil-gyun was gone and he spiralled, he immediately regressed to the only place he was able to get any sort of warmth and comfort, which was unfortunately with Jeol-ho.
All jokes fucking aside, pil-gyun is probably gonna kill that guy.
So.. uke loves Pilgyun, but still goes fucking around?