Invisible

Lately I have felt invisible to certain friends in my life. I can't mention names or get to specific on details. But I have 3 friends, one very close, whom it feels like, I have to do all the work. And even if I do reach out, I rarely to never get a response back. To be honest, it hurts. I felt like we were friends. that's the impression I got, but since circumstances have changed and one is not residing in the same town as me, I feel as though I'm invisible. Like I dont exist unless they want me. When it suits them. And I dont know how to begin to confront them on it. How to express how I feel. Cause when they do acknowledge me, they are great and loads of fun. I miss them all lots and wish I had the courage to tell them how I feel. Lame.