Video gives scientific reason why 'honeymoon phase' ends
'Honeymoon phase' in a relationship is marked by activation of two brain regions, rich in dopamine, a chemical associated with pleasure. Further, an increase in cortisol levels causes feelings of infatuation and obsession. As cortisol decreases, one starts feeling less obsessive. However, that doesn't mean one can't be madly in love with someone even after decades, according to the video.