If he's really doing nothing, then talk to him and change the split.
If you continue they way it is though, don't waste your life thinking "I could have had more.", blah blah It's not healthy.
Your third point is something I've been trying to keep in mind; of course I want more, but I'm conscious of that desire so hopefully it won't get the better of me. I keep reminding myself that "50% of something is better than 100% of nothing". Sincerely though, I'm not interested in owning the whole company out of greed, I'm just conscious of splitting it 50/50 when the responsibilities currently aren't stacked in that manner.
Mainly, I'm just unhappy because he really is doing nothing. We split out our responsibilities--with myself taking most of the hard work--and despite that I've still ended up fulfilling both of our roles.
There's an aspect to this that I'm thinking we may just be operating on different timescales. I do believe he'd come through in the end, but I get the distinct impression his end may be in a year or two, while I'm aiming at considerably nearer than that.
Obviously, the solution to all this is to just talk to him, but I'd rather get my slaps here if I'm being silly before saying anything stupid.
It's gone on so long mainly because we ended up having separate responsibilities. It all sounds a bit silly in retrospect. After he said he'd tackle the business stuff--instead of coding which he couldn't find time for--our responsibilities pretty much ran in parallel without intersecting. Until now.
I've had my head down for those 3 months--baring in mind this is part-time--hacking away, and it's only when I've come to start dealing with things he was responsible for (like, "Hey, you manage to get a VPS for our test box yet?" "No, sorry mate been too busy.") that I've realised that he's effectively done nothing for a good few months.
In hindsight, we should've been communicating more. I shouldn't have let this go on for so long; at least not without some communication.