When you swim in an ocean, you do so without knowing that at any moment a huge wave could come crashing down on your helpless body sending you tumbling into the depths of the unknown.
When you fall in love you fall without knowing that at any moment that wave could come crashing down on you throwing your whole life off balance. Falling in love is like swimming in an ocean.
You swim even though there are 100 different things that could possibly hurt you. You fall in love even though there's that possibility that at any moment you could be heartbroken.