u/Equivalent_War_1813

At least from Palma's side since she has questionable morals throughout the series. Sniffing a letter is a bit excessive. Although there are other warning signs since Palma nearly sexually assaulted Tokio in his sleep and now emotional dependency is a side effect of Nest. Tokio and Palma are being set up as foils to Batista and Hartley; but a common staple of Ishida's writing regarding romantic couples is the pitfalls of being emotionally dependent on someone.

Just an ever shifting view on power and violence

Kaneki use a large kagune to attack Arima/Eto, they get impress, and it ends with them jabbing his eye.

Kaneki manage to impress both Arima and Eto in battle which ends with them jabbing his eye. Since their intention is to groom Kaneki into becoming the one eye king its symbolic that Arima stabs his right eye (human) while Eto licks his left eye (ghoul).

Kaneki associates Rize with his ghoul side. Throughout the series Kaneki is shown to adopt several characteristic; their ticks, worldview, and fashion sense, from the human and ghouls that he meets. One of Rize's most notable haracteristic is that she is a femme fatale which means in this case Kaneki wearing a gimp suit himself isn't trying to be sexual he is trying to evoke Rize in his own way.