Well... I don't think boys necessarily "lie" about loving girls! Sometimes I think people get confused with lust and love.. There are no KEYS to finding out if a boy truly loves you or if it lust.. or even puppy love. I never used to believe in love but from some experience love is when feelings are mutual. two people that honestly respect and trust each other. The person would treat you different from any other lady and give you attention. Like Judy said though choose wisely... it hurts so much to give your heart to someone that doesn't deserve it!!!! You will know when you should open up and experience love... its in our nature!
He has to be trust worthy. Have a good, sincere, honest heart, yet nothing is guaranteed, so choose wisely :)