Hi Jon,

You have really put a lot of thought into this and have a good understanding of how your actions are impacting the relationship.  I am not sure I can add much, but for me, the quickest way to stop acting childish or resentful is to be grateful.  I have a gratitude journal that I write in everyday.  The practice helps me to be grateful in the moment, so when I am with someone, rather than worrying about if it will last or what is going wrong, I am able to enjoy it more.  Anyway, that has helped me.  Wish you the best of luck.