Well you need to escalate, start small will nice comments followed by a light hearted and gentle Neg then escalate so it gets more and more. Do it over the course of a few days or visits. And if she is still being pig headed. Go for the in your face;

"Look i've been hitting on you for the last few weeks, but i just cant figure you out, you intrigue me and i find you really attractive. So i figured id just ask you out for a drink so i can try and get to know the real you better. This whole chatting to you at work thing is nice but id like to be in a little bit of a more relaxed venue for me personally so i can chill out little more."

If that doesn't work your games up move on, there are hundreds of hot cougars around ripe for the picking!

Regards, Saint

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Attraction is the insatiable desire to be irresistibly desired

I retract that last statement. Honestly, from the sounds of things, it seems that you need to simmer down on this a bit. From your last few posts you seem a little too eager to let this happen naturally. She may be older but that doesn't mean all women lose that youthful dignity. She could have an issue, yes. As much as I understand how your feeling, going about it this way could even hurt your chances.

You wanna get her really interested in sex? It has to mean something, to her. By being there for her and ready and willing whenever, obviously it isnt getting the job done. You could be more forceful with your advances and tell her you want more. Another way of doing it is to be aloof. I used to do this all the time in grade school when a girl I liked ever found out about me, and it drove them all nuts that I'd never give a straight answer or dodge it entirely. Why wouldn't it work now? By being aloof, that security of you being there is gone. You could vanish into the arms of another woman and that support you give her mentally is gone. The key to fucking her is her insecurities. You need to be too busy to deal with her, so you can attend to some fine younger bitches. You think an older woman wont miss that attention from a hot young stud? Pleeeease..... she just needs a reality check that she needs to give it up if she wants things her way.