I definitely relate to your situation. I've shared that I would like my wife to try a bigger cock once, just to have the experience. Even though she has firmly said it will never happen I asked if we could just "pretend" and incorporate that teasing/dirty talk into our love making. This was a huge step for her and she has gone from being very awkward to blowing my mind with the ideas and descriptions that come out of her head.
Now, compared to what goes on here this pales in comparison but, their journey isn't mine and mine isn't theirs. I've had to learn that I have to be satisfied with little steps and look at them as welcome improvements in our sex life. I'm starting to see the accumulative effect of focusing on subtle changes. My wife seems more receptive about sex in general than ever before, however that's relative when you compare it to here.
Lots of times I've felt like giving up. I've discovered that I don't like the negative spiral I go into after feeling defeated. My mood seeps in to everything else and I just feel worse. I had to snap out of that. It didn't do anything. That's why I've chosen to be forever hopeful and try to build on successes and learn from the failures.
None of this is easy, either trying to get into it, or apparently managing it after you are. Some people do it though! I've always thought of it as like I was a kid looking in through the fence at an amusement park. I see those people having so much fun and I can't get in the park.