Pleading only seem to go so far when dealing with Kunzite, especially when he seemed to be brimming with emotions. It certainly seemed that the main cause of all those emotions were Endyimon. Which seem to be a problem within itself, Zoisite just couldn't seem to piece together why Endyimon was causing such emotional turmoil in Kunzite.
Never once had Zoisite thought that the cause would be him. That Kunzite urge to kill Endyimon had everything to do with how Zoisite had to awaken Endyimon, instead of heeding Kunzite's warning and leaving Endyimon to sleep in peace.
Zoisite seem to go against everything Kunzite said and it angered Kunzite that he couldn't control his fellow Shitennou.
Kunzite never realized the emotion that he felt was not hate but jealousy and Zoisite never realized that Kunzite even cared for him.