Dear Anonymous,
 
Thanks for posting your question. I know that many parents are struggling with mini "love triangles" and "friendship triangles" among their children at this age. As a side note, I am continually amazed at the intensity of emotions generated among friendship triangles at this age. Almost (if not more so) than love triangles in adulthood! Ah, but I digress...
 
This is a very complicated situation, and I don't believe that you can easily "solve" this situation for your daughter. Rather, I believe that you can use this experience as an opportunity to educate her about friendships and romantic relationships.
 
Regarding friendships, you can discuss with her the qualities that she looks for in a friend (e.g., someone who supports you, someone who helps you grow, someone who you can have fun with, etc). Ask her to evaluate her current friendships and consider, now and in the future, whether she feels good about the way that her friends have treated her. Assuming they are close friends, how does she want to manage a break in trust in a friendship? You can offer some advice about how YOU manage friendships, things that you have learned (I have found children LOVE hearing about their parent's own experiences). Do you typically talk directly with the friend about your disappointment? Or, do you ignore it and let it go?
 
These kinds of conversations will help your daughter to learn skills for managing friendships (and other kinds of relationships). Unfortunately I don't have an "easy" solution for you, but I am hopeful that your conversations with your daughter on this topic will
help her and increase the mother-daughter bond.
 
Best,
 
L. Compian, Ph.D.
Child Psychologist
Education.com