absence makes the heart grow fonder

When someone is speaking of the term: Absence makes the heart grow fonder; they are usually referring to the lack of something increasing the desire for it. For instance, if you are near your significant other all of the time, you will not feel the depth of the love you have for each other as you would when one of you is gone for a length of time and return to each other to realize through the absence how much you love each other.