What does the title mean?

This was on a webpage (so not my own invention): "Meaning of the Title Lost Horizon is a reference to a faraway paradise that can be obtained, but is usually lost by those who need it most."

Wait! Does this also mean putting out doesn't get you love?

The 'horizon' is more an allegory or extended metaphor. If you saw someone gazing off into the distance (or horizon) lost in thought or longing you might say "he's lost on some horizon." Or if you lose sight of some ideal or opportunity - a 'horizon' - that's a lost horizon.

The horizon here is the peaceful ideals advocated by the inhabitants of and embodied in Shangri-La. For the High Lama and for Conway, peace is a lost horizon in the face of man's vicious wars. Bear in mind that WWI is still a raw memory and that the specter of a looming new world war with modern methods of mass killing and air warfare was already looming in 1933. Hitler had just seized the chancellorship and many recognize shim for the despot he was. Lost Horizons is, at its core, an anti-war - or at least the modern escalation of war -- movie, as is the book.

At least... that's my 2 cents. :)