Eren took a small sip of the wine. Nina was horrified by his stunt and wanted to stop him. First, he was not used to with alcohol in general. Second, the wine was made from C Rank ingredients. It was basically a C Rank debuff potion. Eren would die if he consumed it.
But before she could do so, Eren stood straight in front of her and lowered his head to kiss her on the lips. Nina could feel the wine that was dripping down from Eren's mouth into her throat.
Eren had not gulped down the C Rank wine. He wasn't suicidal. He only kept it in his mouth briefly before sending it into Nina's throat.
Nina was still sitting on the log. So she had to look up to respond to Eren's kiss. By doing so she had allowed for a gravity-friendly expressway for the incoming wine.
The insides of Eren's mouth were feeling a little burnt because of the wine like he had put a lump of hot coal in his mouth. But he didn't care.
"Erni, stop doing stunts like these. I can drink the wine myself."