I was asked by this (tenure-track) assistant professor X, with whom I'm in very friendly terms, to collaborate on a project together. X and I work in the same broad area of pure math (topology) but our subfields of expertise differ considerably. At the beginning I was very excited but I've now realized that X is at best extremely inefficient and at worst incompetent. We have been working on the project for some months now and 90% of the things that X says are wrong for very elementary reasons and the remaining 10% are borderline tautological. I'm getting very frustrated because I spend more time correcting his "proofs" (of very elementary claims, not even high level stuff!) than doing actual research. So far all we have is stuff I had proved before starting the collaboration with him which forms the base of the project we are working on. On the other hand he seems to be very keen on us working on a project together and as I've said we're friends. I don't know how to deal with this.
Should I give him some more time to actually contribute in some way to our project or should I tell him that I no longer want to collaborate with him? In the latter case would it be ethical if I worked on my stuff that I shared with him? He literally hasn't added any value whatsoever to it so far.