the first photo is of a natural element, hence that its nit man-made. the shape of the first photo is more geographic then the second photo.
the second photo is of a side walk, a man-made object. the shape of the second photo is of a square, a square that was man-made, had to be put in place.
You mean <em>"Why do [some] </em><em>people</em><em> cheat in relationships?"</em>
Well an analysis revealed eight key reasons: anger, self-esteem, lack of love, low commitment, need for variety, neglect, sexual desire, and situation or circumstance.
<em>Or the world is and humans are just terrible LoL</em>