One is that location plays a distressingly familiar role in romantic relationships (we fall in love with the people who happen to be around us). Another is that casual intimacy goes out of the window for many boys after a certain age - their friends and family have stopped touching them, so if a girl treats them as they normally would another female friend, and does something meaningless like gently squeeze their elbow, it’s the most amount of intimacy the boy has experienced in a while, and it gets elevated beyond its intent.
I think it can happen for a number of reasons.
One is that location plays a distressingly familiar role in romantic relationships (we fall in love with the people who happen to be around us). Another is that casual intimacy goes out of the window for many boys after a certain age - their friends and family have stopped touching them, so if a girl treats them as they normally would another female friend, and does something meaningless like gently squeeze their elbow, it’s the most amount of intimacy the boy has experienced in a while, and it gets elevated beyond its intent.