How would you handle the following issue?

One of my best friends and I have grown apart lately. We use to be called the Bobsey Twins. However, she has a new Bobsey Twin. I don't have some of their common interests and feel slighted. My Friend and I have worked together for 7+ years. We've been through thick and thin together. The 'new' Bobsey Twin also works with us. A couple of weeks ago my Friend didn't show up to work at her scheduled time. I called and left her a message saying I hope everything was OK. She ALWAYS called me if she was going to be late or not coming in. The new Bobsey Twin works a later shift and she did not show up to work. Low and behold they had taken the day off together. She said they had it planned for quite some time. The following day she acted like nothing was wrong and said hi to me. I said hi in a very cooler manner. We had a one on one regarding the situation. I said, but you couldn't tell me you were taking the day off ? What's up with that? She said she's been pre-occupied, yada yada yada.
I've been staying in the background. Any advice?