it was a moment of weakness in a way! wyb felix is aromantic and doesn't know it yet at this point. he definitely craves intimacy, hence the slutty phase, and it's confusing to him why he wants to be close to people but doesn't want to be beholden to romance in any way. after a few tipsy rants about like... hook-ups and expectations and 'why can't everyone be like jisung and NOT be in love with me, i don't want to date', jeongin is like hey btw do you think you're aro and felix is like what's that! and jeongin opens a whole new world of info to his little noggin! and felix is delighted to explore boundaries with that definition for himself, yay felix~