People change and forget to tell each other. –Lillian Hellman
Do not confuse doing nothing with lack of caring about the friendship. It’s about keeping your self respect. When you stop initiating after three attempts, you are essentially doing nothing. You go on with life as if the friendship has ended. Although you might be hurt and confused, when you see them on the street, you wave hello. In other words, continue as if nothing has happened. Maybe they have their own “stuff” going on that you are unaware of. You might even have seen it coming when you realized your values were no longer aligned. Or maybe you have noticed signs of disconnecting such as rude behavior or distancing. Or they just stopped posting. Whatever. Shake your head and say: “It’s their loss”. By deliberately doing nothing you claim your power.