text: Try talking to her and finding out the real reason she hasn't been hanging around.  You're right, it probably has nothing to do with you.  It sounds like she's jealous of the time that you and her brother spend together and feels left out.  Try to include her more and set aside special time for you and her.  So many people neglect their friends for a relationship and it should never be like that.  She may be jealous that you found someone and she's still single.  The only way to find out is to talk to her and keep trying to talk to her.  If your kids are close and you and her brother have a future you're going to be in her life for awhile, whether she likes it or not and hopefully you can find a way to peacefully co-exist.