I have Class N Orchid Endlers and I have been breeding rare livebearers for a time now. Yes, it is true that males will harass the females and I see this even with males of different species harrassing females of another. In general, livebearers should have plant or some type of cover, so it is not surprising that the female seems a bit reclusive. Specific to endlers, they are not shy creatures. However they are distinctly different from guppies.
It is important to understand the difference between guppy as a "body type" vs the true guppy (Poecila reticulata). Many aquarists will confuse mosquitofish, mollies and limia as "guppies". This is understandable as the body type is similar. If you have true bred Endler hybrids (ie Class N or Poecilia wingei) then they will be 3/4 the size of guppies and the males will be very different than the guppy show breeds. If you have a hybrid (ie cross between guppy and endler) then any characteristic of either species could be exhibited.
In the end, these are cute little fish with some amazing colours. If you enjoy them, who cares whether they are guppies or true endlers. I would however add some floating plants so that the female has cover to feel more at home and seek refuge from the attention seeking male. You may wish to also introduce females of other species, like platies or guppies, as the male will then have more distractions.