Growing up, I watched many romantic movies in which two people would fall in love, start dating, and eventually get married and live happily ever after. I've always had a "Romeo and Juliet" perception of what true love is when in reality, there is no such thing as true love. Love obviously exists, but it fluctuates in its "trueness." In other words, it is not always perfect.
To begin, the notion of love, at first sight, is deceiving. For most people when they meet someone they might have an attraction to that person, but that doesn't necessarily mean its love. There's a big difference between love and attraction. On the contrary, there are people that at first don't even have an attraction to a person and only through time are they able to develop any sort of attraction. Basically speaking, the idea of love of first sight often portrayed in "Romeo in Juliet" is not real. It is simply a fantasy, not a reality.
Another thing to take into account is that the path from falling in love to dating and then marriage, is often again a fantasy most of us have, but that is not always the reality. I will acknowledge that some people do follow this path, but in today's world, many people might live together and not get married or delay marriage for later.
Referencing "Romeo and Juliet" once again, most people, and personally I, myself, would not commit suicide for the person I love. If it is truly true love, then one would do anything for the person one loves, and that includes dying for this person. This extreme idea of dying for your lover is again but a pipe dream.
Now that I've talked about why true love doesn't exist, I'll tell you what the more realistic definition of love is. I am by no means a "love expert," but my definition of romantic love is this: an imperfect force that binds two people to share the beautiful gift of life. That is my definition of love, one in which I myself haven't experienced, but hope we all get the chance to.