Passive aggressiveness....is it a cultural thing?

I've befriended a few Korean moms in the area who traveled in a pack every day. They went food shopping together, to the public library, church, each other's homes, etc. etc. What I immediately noticed was they called each other on their cell phones at least 3 - 5 times a day either to meet or chit chat. The mother who introduced me to the pack is my age and has a daughter H's age. It was obvious she wanted to become good friends with me exclusively. Me, on the other hand, found it more convenient to hang out with another mom in the group, who has 2 boys around T's age, since she lives right down the hill from us, her husband is KA like mine, they are easy going with children's messes, and generous with their time and money. You can see where this is going.

The drama surrounding our playdates has been neverending these days. One mom feels more left out, claims to put everyone else's needs first before her own, chooses not to attend when she clearly wants to, feels she rarely gets invited, etc. etc. The victim role playing goes on and on. While I have not been on the receiving end of these laments, I can't help but feel responsible for the waves. After all, they appeared after I came into the picture. My reactions have mostly been annoyance at the pettiness, the passive aggressiveness and her failure to reflect on her own life's patterns when basically,...I should be doing the same.

I feel bad for her yet I still feel justified in my thinking that these issues are solely her issues and not anyones else's. Someone also mentioned that because my thinking is more American than Korean, I would never interpret a no for a yes. To me, no means no and yes means yes. Is that a bad thing?