It's really not okay. Throughout the duration of my relationship, my SO has been like this. Only child. There was some trauma/bad memories that have stayed with her as she becomes an adult. She's not used to being emotionally open and when conflict arises, she has a tendency to flip it on the other person or completely withdraw. Our arguments, while sparing, have never been fun. They aren't loud, physical, or even vulgar. They just hurt, because like you, they can highlight insecurities and make the other person feel like crap. It's wrong, first of all.

My SO is a very loving person, but she has never properly learned how to manage stress well. She will avoid confrontation most of the time -- using the same tactics such as not entertaining my concerns -- but feels cornered when I voice my concerns (i.e, I am pinning everything on her).

My suggestion is to let her know it's wrong. Don't concede any ground or shoulder any more blame than you can honestly admit to. Relationships require a bit of self-sacrifice and forgiveness, but they don't require lashing out or attacking others. My main method of dealing with arguments is: A.) Be firm, B.) Frame the argument as observations that I make (e.g "I'm seeing things this way" or "I think that") instead of accusations against my SO ( "You are blah blah" or "Why are you so?"), C.) Saying I'm sorry/taking the blame for things that I know in good conscience I can work on, and D.) Not taking any extra blame to end the argument. At the end of this, I will just give my SO space to think about things. It's always worked for us, and over the course of this year she has gotten a lot better at mitigating outbursts. Even if the initial stages of an argument can be rocky for us, we always find a reasonable compromise and work on things.

Communication is the only way out of this.