Confidence... that is the number one reason. It doesn't matter if you have the woman you are seeing on your arm or not... the aire of confidence follows you around.
Since I started dateing my new girlfriend three weeks ago, not only do I turn women's heads, but they go out of their way to speak to me (in one case to drive 60 miles to meet me in person). Of course it's nice being Polyamorous in that I can actually see what may come of all the attention.. but with one exception none of them hold a candle to H my girlfriend. And really I'm more interested in finding another partner for my girlfriends husband with my new power... but really when we have a woman as good as H it's hard to find one who can turn our heads.
But yes it's all about your confidence... because the reverse starts happening the moment you start sensing problems in your relationship.
That's the basic idea, I agree. I think your vibe changes when you are involved and you become a self contained unit in the sense that you are just happy being you and don't need to talk to anyone or meet anyone. When you are single and looking, your vibe is more that you aren't complete and are looking for someone to complete you. Not literally, but you have the vibe that something's missing.
My friends and I once talked about this, that they get hit on more when they are involved with someone, swamped with work or a busy schedule with no time to stop and talk, basically at all the wrong times. We decided that someone is attracted to you physically but your vibe sends a satisfied enjoyable signal....and its something people want to get on board with. Otherwise you send more of a signal of wanting something. So, a potential date doesn't want to BE the party, they want to JOIN a party that's already there....or they don't want to be the destination but they might get in on a destination that's already determined. Does that make sense?