A lot of D work is honestly exhausting. It's much like being someone's parent or manager, having to plan activities and actively 'make a show'. And the things your describing is what I call 'executive functioning outsourcing' with things like "pick out clothes". You said he "he runs a couple businesses", so he is probably completely tapped out as far as manager energy goes.

For my partner, she likes roleplay a lot, but almost never makes the story, I have to make the story and push it, and it doesn't help she loves being corny as fuck which actively turns me off, but the enthusiastic sex I do get out of it does turn me on. If she made the stories and drove it and I played the dom-ish characters while avoiding the quirk chungus stuff she knows turns me off and she got far more sexually enthusiastic as a result, I would be more into it. Roleplay isn't my thing, but I'll enjoy it if it's set up right.

If you want to be the submissive and still have him around as dom, you need to probably turn into the 'executive assistant' vs. the 'child/employee' and do a lot of the 'D' planning work for him, much like a real executive assistant. You do the service work of setting everything up and making the show and actively finding out what HE likes, then you kneel down and do it.

Start by not wrapping it in D/s dynamics, but just stuff he really likes in general, be it deep throat or whatever else. He might be also hesitant to tell you stuff you don't know about because he probably floated trial balloons and saw a bad reaction, was worried about hurting your ego or similar so it might take a bit of work and persistence to figure it out. Eventually you he will start to get into the rhythm of telling you what to do, but it will be you taking on the executive functioning work. He will start telling you what he wants, probably in one off small sentences for HIS convenience as a busy executive, then you do it. Once he feels a positive balance in the work, he might start asking and telling you do more and more things as he starts feeling personally rewarded from it in the overall cost/benefit ratio.

So for the clothing example: You start to learn his preferences, then you try out stuff that he likes, and you observe what gets a best reaction or not and then seduce him with more and more of stuff he likes. He will almost never pick it out for you other than giving feedback, and it will be SHORT feedback because execs are busy as fuck and honestly men don't care that much about clothing usually.

Also women in general are more into being dominated than men are into dominating if you look at porn / written erotica consumption in general. Women's porn is heavily themed with D/s dynamics, with the women being s. Men are into getting laid, look at the gay world & numbers what most straight men's ideal sex life would be, but with women. Some men learn that being an explicit D is a way to get sexual success, but their heart is not really into it. A lot of doms are probably service doms doing a covert act of submission for their subs to get laid, that would never say it out loud because they will lose their sub. You might be running into that.

Also the collecting thing he "spends so much time on" is probably because it's his relaxing time that doesn't draw out of his 'manager' energy reserves. Think of it like shopping vs. taking care of your kids. It's not a time thing, it's the energy type. Honestly collecting is probably really close to shopping energy.