I am my husband's 'perfect woman', tho. I chose him after all his bright plumage displays, not the other way around.
But I know what you mean. I think some men and women have differing ideas about this. From my experience, and I mean this generally, men tend to be more definitive about their woman once they've decided on one. She's it, and that's all folks, end decision making process. You know this mindset yourself, Cain.
Women tend to want to keep their options open a bit more, esp when younger. That 'fickle monkey' thing, I mentioned before. I haven't seen too many guys exhibit this behaviour unless they are already in a relationship that they know isn't going to last. Placeholder GFs and that kind of thing.
So, not sure how this helps your question except that, as a woman dating, I would be way more wary of a guy dumping me or choosing some other gal over me. It doesn't seem to be a guy's way unless they KNOW the gal isn't what they really want. Harder to say for a girl, except she might be more confused and fickle?