@charlie4eva2,
Then do it a different way.
It seems an odd position for this - she could be lying on her back, yanno.
But it seems, rather, that there's other things going on, as you have other issues that you're now starting to allude to. Has this woman been sexually traumatized some time in her past? Is there some other reason why she doesn't want to have sex? Not everyone has to want to have sex; do not misunderstand me. But it seems as if there are other things going on here, where she cannot/will not let herself go.