Farther But Closer

Life has so many ironies. Humans tend to yearn for things that are not there anymore.

For example, your family, you live with them, you grow up with them, you get tired of them, then you take them for granted. You move away, then you yearn for them. You wish you're with them again.

Now, why is it like this? Are humans so stupid that when they don't know a good thing when they have it? Why do they yearn for the opposite when what they have right now is so good? Is it some kind of brain malfunction?