This was the story of my late teens and early 20s. (I wrote about it four years ago.)
Not that I didn't occasionally hit on girls in socially inappropriate ways (usually, because I had no idea what the rules were). But the number of times I did that is probably short of the number of times I now know somebody wanted to be a little more forward. Which means that there have got to be a whole bunch of unknown opportunities I passed up. And why did I pass them up? For exactly the reason the boy in the comic does. Because I was nervous that I'd be intruding on the girl's space or doing something creepy. I've learned some things over the years and gotten more confident, but I'm still that way a lot.