Apparently there is a tendency for males to bond with males when located side-by-side, while females tend to bond with females when located face-to-face. NSLog(); offers the examples of "working on cars, fishing in a stream, shooting at a rifle range".
However, what does it mean when holding hands with your opposite sex S.O.? I guess this is a tendency for the males? So therefore, females should prefer to stroll facing one another. :)