Hey, Rob. I would echo GFN's comments. I have a friend who never quite finds the "right" guy. I stand by her right to choose and "un"choose whom ever she wishes to share her time with. My second husband was extremely threatened by her, for some reason. He was a pretty negative person, lots of deep unresolved childhood/sexual identity stuff (EX husband) but I saw absolutely NO reason at all why she had to be analyzed by him as to why she broke up with whomever.
It's HER life.
And it's YOUR life. Because you are a nice guy, you probably will want to explain things to the woman, but beyond that, people have limited understanding of anyone else's relationship, and if, like my ex, they are so very interested/threatened/in need of your excuses/explanation....I say, they've probably got to clean their own house first.
It may hurt to have people get the wrong idea about you, if the woman looks hurt and you like a heel......but stay strong. If you have real friends, they will stick by you and not insist on knowing your detailed motivations.