How can you tell if you really like someone?

Late last night she confessed to her close friend, 'I think I really have feelings for 'him' already.'

How she could be so sure. 'What do you see in him?'

'Well, the way he talks is really cute and for other reasons you don't want me to disclose he he he.....'

'Are you sure it's not rebound (after your break up)?'

'I don't think so kuaaaa.'

So, the question here is, HOW DO YOU KNOW IF YOU'VE REALLY FALLEN FOR SOMEONE AND IT'S NOT A CASE OF PURE REBOUND?

If you smile that silly smile when you receive his sms, does that count? When you don't hear from him, you're so tempted to call to see how he's doing? You try to look you best when you see him? Even if it's just one call to ask a stupid one liner you're estatic?

When is it time to realize he may not be the one you're really after?