I told you I knew when I loved you when I believed I would take bullet for you if it meant you would live and I would die, because dying to save you would always be my choice. And now, I know you'd be the one holding the gun to my head.
Some people aren't really loyal to you. they are loyal to their need of you. once their need changes (like if they found someone else that would keep them from being lonely who I guess is better than you), so does their loyalty.