They have unresolved issues from the past. They are in a sense broken. They never matured into healthy, whole adults. I don't think they know exactly why they feel this way, but it's much easier to place blame than to look in the mirror.
The journey they are on will take them down many deadend roads. For some the search will be a never ending one.
This impossible search for the destination called "happiness" will continue until they finally stop running from themselves, and face their issues.
