What exactly should Luann be apologizing for? She doesn't run her mouth insulting other cast members. She isn't mean or spiteful. She shows up to the other ladies events to support them. So she's self-absorbed and feeling herself? Tell me which of them aren't. The difference is that she has things going on her life and the other women resent the screen time that affords her.
If they've truly been friends for 13 years, and Luann has always been the same, then it appears to be Dorinda's issue. I know that I would have a hard time trusting someone who came at me like Dorinda did in Colombia. Dorinda expects Luann to forget and for their friendship to go back to where it was. Instead, Luann now treats Dorinda like a co-worker, similar to Bethanny. imo, that's on Dorinda.