I Believe, LIR is yet another fancy jargon given by the westeners for 'illicit relationships' to make (appear) it more acceptable to the civilized society.
Here, two young earning individuals (living far from their hometown take the advantage) meet with no clear long term Vision/Mission in their relationship to enjoy on the likes of married couple with no strings attached, with no 'legal obligations' to be held accountable for any wrong doings.
All remains well quite for sometime, but soon the charm gradually falls. Problem arises when either one of them gets serious (if both were non-serious initially) or either one of them gets non serious (of both were serious initially).
To me, it's finding a win win situation for those who don't believe in.. shaadi ka laddu
'जो खाए पछताए..जो न खाए वो ललचाये.. '
Changing it to... लड्डू खाओ बिना पछताए के