I wouldn't be too pushy or obsessive about it to her, just be smart and figure out a way to introduce the idea to her in a way that she might like it or might turn her on in some way. You know her better than anyone so just take a step back and think. Take small baby steps. I had to do something similar myself because i was in a similar situation at first, wife is very shy when it comes to this kind of thing and her sex drive is way down ever since she had our children, but there is always a way and i just took it slow and did little things here and there, found when and what makes her most social and turned on, planned out a few things that i made look like weren't planned and before you know it she was eagerly spreading her legs for other guys.
Im not saying it'll be the same for you or that it will be easy but I think by taking it slow and really thinking and planning out how you can get her to try it, even if it's an abstract idea, you can probably get her to try it one way or another.