My DD has a good friend who she has a lot in common with. They go to the same gymnastics, guides and music group. They see each other at weekends and during holidays and I am good friends with her mum too. They are both 11 and recently my DD's friend has started to go into moods with my DD over all sorts of silly things but mainly when my DD spends time with other friends. She won't talk to DD and is sulky and quiet. I'm finding it hard to keep the friendship with her Mum lighthearted. WIBU to cool off or do I keep going and accept that girls fall out?