The relationship is impossible as they are described as a parallel line but the composer as describing them impossible has said that still, they have met as they are getting married.
Work Step by Step
One of the properties of parallel lines is that they never intersect each other. Thus, the intersection of two parallel lines is not possible. As the composer describes the marriage between two characters of a play as the parallel lines that meet which is not possible. But the composer has still created this hypothetical situation of them getting married.