I was in the same boat as you not too long ago. Nothing was getting better and I realized there was nothing that I could do to make him change his mind.
I fought everyone on here when they told me that I should ask my H to leave, but I finally did it. Its not as scary as you think...and besides..she wants a D anyways, right? So what do you have to loose really? Like stuck said, somehow you have to make her miss you. I too am afraid that separation will push my H further away, but its just a chance I take. Nothing was changing anyway and if he thinks he wants a D so bad then he needs to see what being D is going to be like.
My H is stubborn as well, and everyone was telling me if he left he wouldn't come back. well, we will see about that. Ever since I told him to leave, we have had several dates, lots of phone calls, and we have been getting along great. He even finally told me that he does love me after 4 months of denying he does and on and on and on....
Nothing is a guarantee, but if you don't change anything and don't make things a little harder on her, then nothing is going to change.
Hope I dont sound too harsh, but I am saying this because I felt the same way as you. I invite you to read my first thread if you have time and there is some great advice in there too....