This is the second and the most exciting phase of love. This is the phase when your heart beats fast, you lose sleep, and feel euphoric when you see your beloved. You may obsess over that loved one. It is based on at least four brain chemicals, called monoamines, namely epinephrine, norepinephrine, dopamine, and serotonin. Epinephrine causes the anxious feeling, rapid heartbeats, jealousy, fear, and the strong recall of love emotional experiences.
Norepinephrine causes the increased attention to our partner and the loss of sleep. Dopamine causes the joy we feel with love, stimulates our sex drive, and makes us perceive our partner as perfect, even if they are not. It makes us believe the impossible will happen. Serotonin acts like a maestro, coordinating the activity of the other brain systems mentioned earlier. We all wrongly believe that romantic phase of love should last for a lifetime. In reality, it does not.