Err I seem to have forgotten

Remind me again,

How do you know if you're falling in love?

How do you know if you are in love?

How do you know if you are really missing that special someone?

How do you know how much time is enough for you to fall in love?

12 hours? 12 days? 12 dates? 12 months?

How do you know if its true?

HELP me