How has this manga been going on so long and people still don't understand Seto? All these bros saying "Lol how is this guy not ready to go?" Seto is absolutely 100% ready to go and that's what scares him. He keeps telling himself things like "I don't know if I can control myself" or "there's no going back" and such. Seto is just as thirsty as Anjo, it just took him a while to realize it and he's not sure what to do with it. I just wish it was better explained where his anxiety about physical intimacy comes from. I don't think it's just performance anxiety.
Honestly Seto saying "Look, I'ma be real with you, I'm about to lose my damn mind" is a pretty big step for him, emotionally.