Orion,

There are stages in a relationship and it is usually around this time that the honeymoon stage is over and transitions into the more serious stage… or not.

You are building a case of not wanting to be with your gf; not wanting to be a step father, not having things in common with her, having more energy than her.  Also you have identified your own personal issues of the lack of self esteem, that you lack the courage and integrity to breakup with someone you don’t want to be with by being passive-aggressive.   You mentioned some specified some built up resentment as well.

You said you have started therapy.  Good for you.  You owe it to this woman to be clear on whether or not you are going to move forward with her sooner rather than later.

In your post, you have not mentioned any of the reasons why you want to stay with her, only reasons why it is not working for you.  I suggest that you fully look at yourself and be clear on what you want in a long term, marriage partner.  Also be clear what you can truly give to the relationship, can you really love this person, with not only your heart but in terms of deeds and actions.

Mark