Thanks for the new thread!
I feel like Iris was just so comfortable in her friendship with Barry after all these years and he never really said anything to her about his feelings so she never thought about him in that way. Once she was confronted by those feelings ep 15 showed that even though previously we didnt see it as her POV, she was in fact thinking about him and its very possible that she is just scared to give in to those feelings bc of "what if it ruins their bond" "what if it all goes bad??" There's a bunch of reasons why she doesnt want to acknowledge her feelings for Barry imo.