Earlier quoted context omitted.
I'm inclined to agree with much of what you said, but I don't think sexism is always at fault here. If I were that person who struck up a conversation with your fiance, I know I would personally find it difficult to make the "first move" in initiating a conversation with you. Is it because I'm sexist? No! I'm not a very extroverted or social person and I find it personally very difficult to make initial contact with…
You're not sexist, but you have less problems breaking the ice with men than women...
I feel off-kilter speaking with strangers that I find attractive in a professional setting; I have to keep telling my brain to ignore itself and act normally. This isn't unique to any gender -- the other day I was ordering lunch in the neighborhood, and the person behind the counter was mooning at me to a degree that actually made the interaction uncomfortable.
I don't take it personally; that's how people are, myself included. I know it can be slightly uncomfortable, but as long as we're trying to be professional with and understanding of each other, things generally work out.