Nooo, this is so far from the truth! To make it simple it goes like this:
Suzuki (topping) had sex with Norman (bottoming) because sugiki doesn't want to bottom (to be submissive/let go of control to be precise)
About sugiki finding out, I'm not sure. He had sex with multiple girl as well because he got drugged (?), so tbh what suzuki did ain't as deep as what everyone says (imo).
Suzuki had sex with Norman because of stress relief/ serves as their escape. The fact that Sugiki and Suzuki broke off and did not see each other was stressful. Not because Sugiki didn't want to be the bottom.
They broke up since Sugiki seemed to be having a pure and perfect love with an idealized version of Suzuki.

So there are extras end of each vols that are not being translated or even here.
They already had their fingers in their asses.
Vol 4: Sugiki put fingers in Suzuki's ass. This is before Suzuki had sex with norman.
Vol 7: Opposite of vol 4 happened. Sugiki wanted to try getting fingered. But Sugiki doesn't feel it much as Suzuki (he is more sensitive).
Vol 8: Different alternate universe-> They have a daughter and have animal ears. Suzuki wanted to be penetrated already. Sugiki says Suzuki so moist down there that they could probably do it without lubrication. But Sugiki won't penetrate until 10 Dance competition is over TT-TT but they did explore more with each other