It’s not me, it’s you. But what if it is me?

I love your teachings about people getting to choose to like peaches or not. If they don’t like peaches, then that’s fine, I’m not for them.
My question is, what if you’re a rotten peach? 🙂 You were coaching someone about setting boundaries for things that her mom says and her mom left. She said that her family says that she is oversensitive, etc. What if she is and yet she keeps telling herself, it’s not me, it’s them and they just don’t like peaches? What if it really would serve her to take a look at herself and decide maybe she is the one who needs to change?
I’m asking this with her as an example, but for use in my own life. When do we know when we should change because we are causing our own problems and when do we just decide they don’t like our type?