"I love you" are just three simple words, but together they hold a lot of meaning (at least we think they do). Some people over use the phrase, some under use it, and the majority of people forget its meaning.
You may be able to recall that as a child many adults preached to you that, "actions speak louder than words." If you really think about this phrase you might realize it holds a lot of truth. "I love you" are just three words that hold no meaning if they are not supported by actions that represent that love. So if we can understand this then why do we still yearn to hear those three words from our loved ones?
I grew up not understanding why my grandfather never said I love you to my grandmother. At first I thought maybe it was because he only said it when they were alone so I asked my grandmother. She said that I did not understand that it is not important to say I love you, but to show it. She then asked me what my favorite fruit was and I answered plums. She then asked me when you come over what fruit do we always have and I said plums, in which she answered, "that's love".
Love is about going out of your way to show those that you say, "I love you" to that you genuinely mean it. My grandfather's way of doing this for me was filling his home with the fruit I liked and that's when I really began to understand it is not about what you say, but how you act.
Still, it is natural for us to say "I love you" before we go to work and expect to hear it from our loved ones before we go to bed. Even if we know we are loved by the actions the people in our life take to reassure us, it will still always be nice to hear.
Just remember that it is likely in your own life that the people who say I love you the least actually love you the most.