We use 'I love you' so much, that nowadays it doesn't mean anything. It's just another lie.
When you star dating with someone you're always saying 'I love you' the problem is that you're lying. You can't fall in love with someone you met a couple weeks ago. Unless you know him or her since you were children. We have to be very sure about our feelings before saying 'the word', because, it seems like an ordinary word, but is more than that, it's one way to say what you feel. You can hurt someone important lying with that.
Besides, when you are a teenager you can't be sure about your feelings, because hormones influence with what you feel. They are always trying to confuse you, and the most part of the time, the do! We have to try not to say that word when we are teens, it always ruins everything.