I agree with magdlyn....the list of variables is too long. Day to day stuff wont be as big a problem if you don't live together and she is in LDR with the other guy.
Coming home from a hot date "wet and ready to go " doesn't necessarily translate into her wanting you.... and I would go a step farther than Magdlyn and say some may be turned on and others ...repulsed or turned off...not just jealous.
Read my thread sloppy seconds .....I'm kidding last week sage brought this up and I made the joke it would be a good thread title.... Sorry.
Day to day stuff that bothered me ...not remembering what she told one or the other ..... scheduling time with my so called partner ....like booking a conference room. I felt she did things out of obligation and not true desire .....being there but mind and heart not being there. But being the new guy none of this type stuff would really apply.
Why is it so important to be the primary? Whats special about that for you? She clearly isn't or wasn't in a rush to make the declaration....what was her resistance.....perhaps too much structure.