I feel like Author is just bad at incorporating lewd elements into an ongoing story. They also expressed their wish to bring back the lewdness on Twitter apparently.
So 1st chapter really did happen, it was probably just easier to draw lewds before it became so wholesome, and now it's too vanilla to delve into freaky public masturbation.
But who knows, we might see 1 other lewd scene in the next 20 or so chapters lol