Men are dense and women are indirect.
I know these are generalities, but it's sooo freakin common that it's a well-known trope.
I'd actually go a step further and say that it's not so much that men are "dense" as it is that they are full of self-doubt...I.e., seeing the advances, knowing they are there, but not believing that they are actually intended for them, or it's a joke/prank, or for whatever other reason, they convince themselves that it's not an advance and they are misinterpreting.
IANAD, but I'd guess this has more to do with mens mental-health awareness than anything else.