Hmmm...
Not sure. I think when you've let the opportunities to turn the table on her pass you can lock yourself in the SUB path.
I'm not super familiar with her variables - not a dev of Come Home, just helping out - but I can sure take a look at your save. Maybe I can help.
The game will be complete with update #20, so five more to come.
At the moment RJ has plans for 18 endings, one of which will be harem-style (dev confirmed). It will probably not include all 20 LIs, though. This is mere guessing, but since not every one of them gets a solo ending, I guess those will stay out of the harem.