Obsession or addiction to a person can happen, especially if you love him and like and enjoy the relationship and company. This can cause physical problems also as stress to remain far from the person, can cause hormonal and neurological changes in the body which can affect the organ systems. The heart rhythm may be affected. This would need medical intervention by your physician in the form of medicines, and relaxing techniques like relaxation exercises, breathing exercises, yoga, meditations etc.
Please feel free for your follow up questions.