Teru is an established flirt and was fine in the relationships he had with girls he didnt really care about. Like he knows how to date and usually doesnt think much of it. It’s a status thing.
but the second he actually WANTS to date someone hes a fucking anxious mess and gets terrified of eveRYTHING. He still will flirt outta habit but anything from the OTHER person makes him flip. “wanna get lunch” will throw teru into an hour long panic where he upends his entire warddrobe, considers cancelling at least 8 times, and being filled with immense self loathing most of that time
it makes him terrified of dating anyone he actually cares about so I headcanon him as prolly being avoidant of dating anyone he actually really liked
also though this applies to non-romantic relationships! Teru hasn’t really had real friends before so he gets skittish about hanging out with people!