Will drifting teenage friends cause their mothers to drift as well?

My 13 year old daughter and her best friend are drifting apart. There doesn’t seem to be any one specific reason, but I am not totally sure. I think it’s just because of doing some different activities. And I know that friendships do sometimes just naturally drift apart.

Over the years, our families have grown very close. We vacation together and travel together for our daughters’ dance competitions. I have become very good friends with her mom.

I feel sad and worried that their drifting apart will come between our families. And between me and my friend. I don’t know what to do. Should I talk to the other girl’s mom about this? Should we stop doing things together? Is it OK to continue doing things together?

I overheard another friend ask my friend if our girls are still “close friends,” and my friend replied, “No, Not really.” This broke my heart. I feel sad for me. Sad for the other mom. Sad for my daughter. Sad for the other girl. (Although logically, I know I can’t actually feel their feelings.)

I don’t want the girls to drift apart. I tried to talk to my daughter to ask about it, but she shuts me out. She says she doesn’t want to talk about it.

Here’s my model:
C: My daughter and her best friend hang out less often
T: I am worried that this circumstance will come between our families
F: Sad
A: Actively worry and try to problem solve in my mind
R: Continued worry