Because there are no diagnostic criteria for ASA yet, it's difficult to say whether or not any of the above behaviors would be included, and research into adult separation anxiety is currently very slim. But there are reasons to believe that ASA is a very real problem, and affect the lives of countless adults.
Symptoms of Adult Separation Anxiety
Because there has yet to be a clear diagnostic tool set forth to better understand separation anxiety in adults, it becomes difficult to tell what is a symptom of ASA and what may simply be an adults personality. The best way to understand what ASA is, is to view the symptoms of separation anxiety in children and see how they can manifest as adults. In children, symptoms of separation anxiety include:
Distress when attached from a specific figure or figures.
Excessive worry about losing these figures.
Anxious, "worst case scenario" thinking about separation.
Trouble sleeping when away from a specific person.
Physical complaints when separation appears eminent.
One might also add the belief that the person cannot live without another person, or that their quality of life will suffer dramatically.
Adult brains are much more advanced that the brains of children, so it's likely that adult separation anxiety will reveal itself in different ways. Nevertheless, severe distress at the thought of being without someone is very likely to be a problem of ASA, and some variation of the above list would likely fit into any diagnostic criteria.