I really think it's important to think about why you do most of everything. It's possible that it's for reasons that are entirely about Dark Boyfriend, but it's also possible that it's a dynamic that developed gradually over time in your relationship without either of you ever really noticing it.
Seriously, I had something very similar happen to me. When DH and I moved in together, I was unemployed and he was a student. In the grand scheme of things, I had the most time. Even after I got a job, I spent a good year or two being not really busy enough at work, so I still had a lot of time on my hands.
Because of that, and because my personality lends itself towards doing things myself so I can be sure they are done the way I think they ought to be, I took over a lot of things. DH is not naturally good at keeping track of details, but I am reasonably good about it. DH is not naturally good at managing finances (he hates math), but I enjoy it. DH has also been in graduate school for the entire time I've known him, so he's had a lot of other things he had to keep at the forefront of his mind -- I didn't.
But about a year and a half ago, my job suddenly got a lot more intense than it had ever been before. I was (and am) pushing all the limits in terms of the level of work I am doing and the amount of it. When that started, I started forgetting things at home and getting very frustrated with DH that he wasn't doing more. I felt like I was his mother and had to take care of him, on top of earning the majority of our income and having to work outside the house while he sat at home in his pajamas to do his work.
However, in actually talking with DH (and fighting with him) about that issue, he made me realize that a lot of the reason why he wasn't stepping up to help me is because I had made it very clear early on that I didn't really want his help. I was more capable, in the beginning, and so I made it difficult for him to help me. If he didn't do things the way I wanted, I criticized him for doing them wrong, so he eventually quit offering. In other words, I was taking care of him only because I'd more or less signed up for the job.
Things are a lot better for us now, but I really had to change how I was thinking about the work in our relationship. If I was going to expect DH to pick up some slack, I really did have to let him do it in whatever way he wanted as long as it resulted in the desired outcome. So if he does certain things differently than I do, I don't complain about it as long as the outcome is the one we want. Getting to that point required both of us to work a little bit at it -- DH had to get back into the habit of doing things that I'd been taking care of, and I had to find ways to trust that they would be done in a satisfactory way. What helped with that was me helping him take charge of things, in the sense that he would tell me what he intended to do to make sure something got done, and I would ask him what he needed from me in order to make it happen.
So it's possible that there is something other than that going on in your relationship, but some unhealthy dynamics grow out of situations that used to work just fine. The trick is in seeing how it came about and why it's no longer working so that you can jointly find a dynamic that does work for both of you.
If that is what's going on with you and Dark Boyfriend, it was important for me to remember that my DH was and is not feckless -- he was entirely capable of taking care of himself without me, and he can certainly take care of himself now. I'd gotten into the habit of thinking that he was just no good at it, which wasn't true and wasn't fair. There are certain things I'm better at, but I'm not better at everything related to responsible adulthood, and I needed to stop acting as though I was.