Fear of losing someone you love is a common fear. (Or something happening to someone you love.) These fears comes from a great love. The fear is love. But once you realize the love, and take action on that, there is no point to the fear. Fear is immobilizing, love is energizing.
Remember, the biological reason for fear is to get us to act, after the action, the fear is pointless. (Worse than pointless, as it hurts you.)