What makes teenagers not able to understand love?

I would like to ask if love can ever be known to us teenagers…I’m sure that there is a small chance we do. But is it the easy lifestyle that most of us live nowadays that make us take everything for granted and thus not able to properly appreciate until a later age? Or would it be because true sacrifice is something most people don’t really understand until they are older? Or could it be true…that people are nowadays mistaking lust for love?
(To be honest…beyond “sacrifice”, I’m not very sure what love really is).