When

When you just start off as friends

When you find out she's full of surprises

When you begin to enjoy talking to her

When you talk to her almost every day about almost anything

When she's the first person you want to tell everything to

When you both talk and you feel more comfortable with her than anyone else

When she becomes your motivation to become better at anything you do

When spending time with her was the only thing that mattered to you

When she looks at you and you forget to speak

When her smile can make you motionless

When you realize she makes you feel special and nice inside

When you begin to feel emptiness whenever she doesn't talk to you

When you begin to depend on her for your happiness

When she's the one causing you pain but the only thing person that can make you happy

When you fall in love