I get where Naomi is coming from. My best friend started dating my ex after we broke up once. She isn't my best friend anymore. It just really made me doubt if things were ever real between us. I was really young but I had the exact same feelings as Naomi and I went through my mind every time they talked together - every thing he said about her and her about him etc. I dated him for 6 months and there was plenty for me to go over in my brain - so for Naomi she has 20 years of stuff to question. Plus Sam and Addison have said that they did flirt in college - so Naomi's question of if she was the second choice seems to have some validity.
Also, Sam got mad at Naomi last year for dating someone that he was friends with and told her that she could at least go out with people he didn't know - seems to me that Sam is being a bit hypocritical.
Now -Naomi does annoy me but I get her point of view.
I would like to see Addison with Pete - he seems her best chance for normalcy but they need to get past Sam and Violet first.