The entire world is governed by the law of gravitation. Not every time we use our intellect to distinguish between reality and delusion. At one time or another we fall prey to an illusion. The attraction or repulsion is nothing but nature. Do we still give any importance to the first doll/toy that which received from our parents?
It is quite natural for babies to discard the old dolls to new ones. Likewise, we can't settle with one wish . It one wish gets settled another one pops out. It goes on like this till you get buried or cremated.
The normal reason behind extra marital affair or pre-marital affair is "normal is boring" Our physical urge forces us to do something "spectacular" at the same time, not being caught by others because of our act.
People call their love or classify their love as "platonioc love" (ofcourse, their love is platonic till they find a new companion If you are deft enough , you can run two trains in parellel lines just like in mumbai make sure they don't run in opposite direction) As far as human beings are concerned there is nothing called "platonic love" we are all governed by pulls and repels function of this huge magnet called Maya (Illusion).