Scientifically it is a proven fact that when serotonin 2a rises in the blood of people who are crazy-in-love. So, yes, it’s a chemical fact that love-at-first-sight happens, causing neurotransmitter levels to change. This one stays up generally no more than 30 months. When the serotonin falls, that’s when you fall out of love or move to the second stage of love—reward love, where you feel rewarded to be with your partner, but you’re not obsessed all the time. If you’re asking where I came up with this, well…I wrote a book on it.