I have a friend who I've known for 5 years, we met through taking our DC to the local play group. Last year she switched schools and her DC now attend the school my DC attend (I recommended it as she wasn't happy with her school).
She still chats to me in the playground at drop off and pick up, but only when there is no one else about. We occasionally meet for coffee too.
Recently I've begun noticing she has created a big social life around other school parents, lots of dinners and lunches with other sets of parents. What I am finding odd, is that she has never invited me and DH to anything. I find it strange because some of the other parents she has only known for a few months. It's also odd that we chat about our plans for the week end, she always says "we're having dinner with 'friends' ", rather than saying the names of the people that we mutually know. Why be secretive?
I do have other friends at the school and obviously hear about these nights out and lunches. As a long standing friend, and our DH's are friendly too, I wonder sometimes why she excludes us. It makes me feel a bit low if I'm honest.