That's because human beings in western society are wierdly messed up over sex.
Though in my case I figured out the consistent common beats of flirting / courting in my late twenties and realized when I was sixteen my aunt was totally hitting on me.
So a combination of societal sexual hang ups, neurodivergence and family social dysfunctiob kept me celibate until 26.
I've tried to err on the side of caution on that myself, because it's pretty embarrassing to act like someone is trying to hit on you when they're not, on either side. I've had people act like they think I'm flirting with them when I'm not also which is awkward.