What made Flash Gordon completely irresistible to Mongovian females??? All the females Flash encountered immediately lusted after him. And it WAS lust- love doesn't even enter into the Mongo humanoid's mind according to their own testimony...
In the original somewhat cheerfully racist comicbook the yellow Mongo people had apparently never seen a "white youth" like Flash... But in more recent versions (other than the SciFi abomination, we'll forget that one forever henceforth) he is still El Studdo. It's a bit like the many romances of Clark Kent on SMALLVILLE.
It definitely plugs into some monomythic trope somewhere but I haven't really delved into the exactitudes of it yet. More on this when I have. :)