Can you remember back to when you first met your partner? Butterflies and infatuation in addition to lots of other positive emotions were probably part of your story. You may have felt a rush of euphoria, excitement, lust, attraction and finally if there was enough of these addictive ingredients and they have been alluring enough you became attached to each other. All very heady and intoxicating stuff so far, and all well explained from a biological and evolutionary perspect