This relationship was simply you as a Beta orbiter both to entertain her while she continued to look for a higher-tier replacement and also to have as an "in case of hitting The Wall" fallback husband - and she had come to the conclusion that you weren't good enough to keep around for the latter, probably because she realized that she would need to put out to keep you around. IOW, she hated the notion of your peniis in her so much that she would risk hitting The Wall without a fallback.
I have had a few girlfriends like this, and I seethe in anger when I look back at not being able to get poon from them.