"Love is all there is - all the rest is an illusion." I'm pretty sure I read that somewhere. But I suspect you could be referring to this "falling in love," we hear so much about.
Falling in love can't really be called a myth. It is is the appearance of someone who seems - at the time at least - to satisfy a need we have built up in ourselves for 'connection' at a deeper level than we have to date with anyone else. It is based on the feeling of 'need.' This need, I venture, goes deeper than simply intimate companionship and sex. It is almost an 'ideal' in our mind and hearts that we strive for and feel we have found, albeit temporarily in many cases, when we "fall in love."
We've all seen the movies, heard the songs etc about falling in love and, of course, bought into them, probably at a very young age. One can have a series of relationships but falling in love goes a lot deeper.
How does the song from the musical South Pacific explain it? "Who can explain it...who can tell you why...fools give you reasons, wise men never try."
I guess I'm being foolish trying to explain whether love exists or is just a myth. It does exist. It is not falling in love. The feeling a mother has for her child is love. The generosity and sympathy you show to a friend is love. The spontaneous act of giving a few dollars to a homeless person on the street is an act of love.
Yes, love exists. And it isn't a myth.