The only thing that I can think of is that you probably don't give off the air of being approachable, so that's why men don't approach. Also, if you're trying too hard and bring a boatload of expectations, that's a very strong vibe being given off that a lot of men pick up on.
Have you ever just gone out to have fun, meet people and that be all your evening is going to be, or do you go out with the express goal of meeting your next boyfriend?
Men can be attracted to women in sweats with their hair in a ponytail at the gym IF she appears to be approachable. If she is closed off, energetically, because she's enveloped in a cloud of unspoken expectations, then they're going to take a pass on that woman.
People treat you the way they feel about you
If you choose to remain with someone who doesn't treat you well, you cease being the victim and become the volunteer.
~Derrick Jaxn -- look him up