Thanks for your advice! I'm definitely hyper-aware of where the 'cheating' line is and not intending to take any steps towards it. I would never want to engage in anything close to that, not least because I believe that would not constitute polyamory. I completely agree about saying no to uphold values. What you said about couples opening/dating close friends imploding makes sense and our friendship is definitely more important to me than anything else, so that's why I'm focusing on letting it go and placing her firmly in the 'friend' box in my head (although my post probably didn't come across like that because I was just venting my feelings).