The term "earthbound," is usually applied to a person who commits suicide and is also based on the supposition that there is a specific "time" for everyone to pass through transition to the other side; a time when the separation of soul and body is "scheduled" to happen.
At this "time," the separation is supposed to be definite and complete. If you take this point of view, a separation by suicide does not happen at the “right time” or is not scheduled, and therefore the division of the soul from the body is delayed. A natural resistance to separation is set up, and the aura of the soul sometimes accompanied by thoughtforms and emotional content, lingers in the vicinity of its physical counterpart, although eventually it too separates completely, if not by natural withdrawal over a period of time, then by the time that the soul and body were “due” to separate. So, even according to this point of view, there is an end to being earthbound, and the soul continues its development through further learning, though somewhat belatedly.
There are those who hold other viewpoints on this subject and one in particular disagrees with the idea that there is a "scheduled" time for passing to the other side. Some are of the opinion that there are “various windows of opportunity” for this to occur. The opinion is that there is no predetermined time for passing over for those persons who feel that they are the masters of their own destiny.
The belief is that during the course of a lifetime, a person is constantly adjusting this time of passing by acts, thoughts, prayers and decrees. As the person develops and learns, the karma is adjusted to each new cause that the person puts into his individual Akashic record. Thus, the "time" of such a person's transition is not a factor in being earthbound.
From the standpoint of metaphysics, nothing is ever separated in the universe, and so the whole question of an earthbound soul is clearly academic. Soul is universal and ever present in its manifestations. As for the apparent separation of soul from the body, this is as effectively complete when the body ceases to function regardless of the manner in which the body reached its demise.
The concept of being earthbound was, in the past, an allegorical description of a mystical law, and as allegorical descriptions so often go, it came to be regarded literally as some physical habitat. The point in question often relates to what is commonly termed a ghost, a phantom, or a phantasm which has been created in memory of the one who has passed over. It is not the actual soul of the person who has passed.
As it is written in the Holy Books, the Masters teach by parables and allegory because it is often easier to make an impact upon the consciousness of people through allegory than it is to make any impact upon them by the explanation of a natural law. So the concept of "earthbound" evolved as a way to make suicide appear undesirable and as a way to prevent people from committing suicide.