[ ... ... Whenever Sasuke sees Yukimura act like his old self, it makes Sasuke bury his stress and darkness even deeper into his non-existent heart. ]

You don't want to darken that light.

[ The metaphor is different, but Sasuke gets why Zenitsu hesitates. Still, it's too late; the damage has been done. ]

After you apologize, I think you should tell him that. It would help explain your actions.

[ Just giving advice Sasuke wouldn't ever follow himself. Yep. Their situations are different. Zenitsu is human. Sasuke is a ninja. So, giving but not following his own advice is perfectly okay. ]

And then... maybe you should work towards telling him that thing you want to forget.