I'm not in a sexless relationship, but my s/o has a lower sex drive than me. I'm entirely sexually available to him, and I have tons of lingerie, costumes, sex toys, props, BDSM gear, heels, you name it. I've told him about dozens of fantasies over the years that I'd like to try. I'm a bi switch with a penchant for group sex and dirty talk, and there's only a few (truly painful or vile) things I wouldn't be up for and enjoy in bed. I love to please and I LOVE sex. I have no problem at all initiating- hell, I was the one to pursue him sexually at the start. And not just in the dry 'hey, wanna fuck?' way- I put effort, passion, and creativity into my initiations. I lavish him with physical affection sexually and otherwise. I also have pretty good self-image and have no trouble getting naked and freaky with him. To top it all off, he doesn't watch porn with regularity- maybe a couple times a month. I mean, it's possible it's happening more, but I'm not concerned- we've shared an apartment and a PC for 4 years, and I haven't caught a whiff of excessive wanking.

For a good 2 years the sex was steeped with routine and reluctance on his end. My advances were rejected plenty, even for absolutely shit reasons like 'I'm watching a movie' (The Dark Knight, which he'd already seen twice). It took years of sustained communication for me to break through to him that oral and missionary alone just wasn't enough. It took so much goddam effort to get him to relax a bit and enjoy something other than the entirely vanilla. He fears embarrassing himself so, so badly, that he used to rather not try at all for fear of ruining sex for himself on a permanent level. It took so many conversations to understand each other and find ways to make it work. It has involved a ton of creative strategies and effort on both our parts. This effort is still ongoing.

There's a point to this post that isn't all 'me, me, me'. Some men aren't so easy to unravel. Generally my s/o leans towards the responsive end of the 'responsive/spontaneous desire' model. On top of that we were working with a sex drive that is a bit lower than average and more than a touch of performance anxiety and fear. And no, I can't point to pornography as the culprit of his pathology. His sexuality just really, really is that complicated. The only reason I kept at trying is because we've always had amazing chemistry and the effort to understand one another and implement changes was always there, otherwise I would not have bothered. Interestingly enough, he identifies his love language as 'physical touch', but sex is a small part of that, as he prefers to be massaged, held, kissed, caressed over sex, but that is what he responds to to help get him in the mood. Not sure if that's what you meant by romance, but it sounds similar enough.

I get the temptation to make broad sweeping statements based on your own experience (first hand and anecdotal second hand accounts), but there are indeed outliers. My s/o is one of them. I have applied the advice you gave here from the start, and it didn't work- what did work was ongoing communication and showing him lots of non-sexual affection and love. Men and women might have different levels of sexual urgency and what have you overall, but it doesn't mean that men are uncomplicated beings. Some are, some aren't. No two people will have the exact same sexuality and buttons to press. Helpful advice in these situations is often tailor-made.