Now the most important hormone that is key in love is the hormone serotonin. in this hormone our brain keeps the person we are in love with in our thoughts all day long, or what is known as ‘love struck’ and because of this "your new love keeps popping into your thoughts."(Arun, Arthur). This is key hormone in order to fall in love because it keeps that special someone always in our mind, and maybe love is a chemical change in our brain, maybe love is caused by a hormonal change in our brain.