The most scary thing of falling in love...Is the part before you get together:
Fast heartbeats, The dreaming, The smell, The touch, His smiling face... really everything about the person you like so much, feels like a weird love obsession. Falling in love.
If the person loves you back, you'll be happy when you're together, but the first stage in your relationship, is very hard. Everything feels kinda awkward, and you don't know how to deal with it in the first place.
The most painful thing that can happen is that the person you've fallen in love with, is not loving you back, and never will be loving you (kinda like sakura who loves sasuke XD, just a little example). You'll have to go through a hard time... and that's what I always feared for.
Afraid of falling in love? Yes... but, if it turns out right, being afraid will lose it's meaning, because the love of a person will make you feel happy, save and comfortable.