Maybe but if he hasn't seen the aura of "horny" guy then how is he too know that. He IS a virgin and haven't come accross these types of emotions before. And maybe the Colors' of the auras differ from one another because the "neutral" aura differ from person to person
This is his first relationship, not to mention he's the first person he's gotten close to.
plus he tried shutting himself out from others, cuz he purposely didn't want to see their auras and maybe never came across anyone pure or tourney ( which i doubt would be feelings displayed outside of the comfort of ones house)
this is stupid. how can u not know what each color mean after having this power ur whole life