Meh. I think the first love is the only love thing applies very strongly to the human psychy. Because in most cases, unless it was a rushed relationship when you were in 5th grade and you only held hands but called it love, you would have such a strong emotional attachment to this single, first person, who, even after you two split up, you always have a place in your soul for him/her.
That said, I believe that is just the premature, more true love, based purely on emotions and hormones, whereas the later, more rational and mature love, is based on many other factors other than sex appeal, and social compatability.
To support my statements, picture the millions of young people who fucked up their lives by falling in love early and pro-creating like rabbits, when they are 16. They are incredibly happy, and crazy in love with this first, true love, yet it was, as stated, premature.
