So you've tried something. So what? Try again. If you want to continue to live in a sexless marriage just continue with what you've done. It's obviously working for you, right? I mean, you think you've done it all, seen it all and you're willing to just sit there and let your life drip away until you're too old and feeble.
This is exactly what I've been doing for the last 15 years. Trying something new all the time. At one point, I was trying so much that it was driving my wife nuts. She could see I was real busy doing one thing or another to try to improve things so that SEX would be expected. So the new thing I've been doing lately is settling down and just giving her some space. She asked me to do this several years ago, "If you just stop pressuring me, things might improve." Well, they did improve for her -- no pressure. But no sex either.
