In quick and dirty terms, Euclid's 5th has 3 flavours:
Given a line and a point,
1 - Flat/Eucidean - 1 Parallel line through the point
2 - Elliptica/Riemannian - 0 parallel lines throuh the point
3 -Hyperbolic/Lobachevskian - infinite number of parallel line through the point.
1 is always true in the abstraction of 'school' Euclidean geometry and if space is flat.
2 or 3 is true dependoing on how space is curved.
Given that the curvature space is governed by the distribution of mass, it is likely that there are regions of the uniniverse that have space that is flat, 'postively' curved and 'negatively' curved. That seems to imply which flavour of the 5th is true depends on where you are - ie that 'the truth' varies from place to place! If we suppose reality to be 'what is true' is it, er, 'true' that there is only one reality?