After an hour or two or three, when one re-call what he said and what his partner said during fight he finally realizes that may be this fight can be reason of his breakup. The fear of breakup and losing that person is called love. Hence sometime fighting becomes the wake up alarm for the lovers and they run to their partner because they can’t imagine what their life would be without that person. This realizatdion strengthen the bond of couple and sometime this type realization feeling keeps two person connected for the life time.
For example look at our Bollywood films. When hero realizes that he gonna lose his love of life he rushes to the airport before he lose her forever.