They make everyone's head turn without realizing it, but they are unable to seduce the one guy they have a crush on even when teaming up. That's some kind of Greek-mythology karma hex that's going on here.

Greek mythology has very integrated the concept of ironic punishment in it, you know, the whole idea of a character affected by a prophesy actually trying to avoid it ends up causing it, in other words, bad shit happens because you try to avoid it, good shit happens because you let it come to you.

If you want a more philosophical view on why is like this, the Greek had the idea that hope was a bad thing, because hope is always the source of despair (despair is basically broken hope), and because of that the one true thing that could brought you happiness was acceptance.

The irony here that Triplem is trying to explain is that these 2 beautiful women who can make everybody in love with them in a matter of seconds are failing to attract the guy that they actually like, even when this guy in particular is a rather average-simple one.