Does it matter if he won't say I Love You?

This topic is a little different than my usual topic but it's something I've been thinking (and perhaps struggling with) for a few weeks. If your significant other can't (or won't) say I love you does it matter?
Are these words that are important? Do we, in our western culture, place too much emphasis on these three little words?
I've been in relationships in the past that didn't last despite being told I Love You. I have a good friend who just broke up with his girlfriend and they had said those three little words to each but yet they only lasted about 6 or so months. What is it about these words? Why do we only think our relationship is credible once we have heard these words? In the end, they don't mean that the relationship will last. But somehow these words bring comfort, hopes, and dreams.

So if you are in a good relationship where there is mutual respect, you have a lot of the same values, dreams, and goals, you love being together, and everything is good............does it matter that those words haven't been reciprocated.