Polly, have you tried maybe joining a local songwriters' group, like your local NSAI chapter? It might be possible to find such a collaborator there?

Polly, I'm wondering how much time you're giving him to learn your Songs.
With a written Lyric sheet and the chords printed over the words where they change, perhaps each Bar if a single Chord continues through more than one, and familiarity with the Melody, via recordings, he should be able to learn them within a reasonable time. I'm wondering what the explanation is for not having learned them. 
If he can ad lib through them with appreciable guitar accompaniment, he might be valuable to you as he becomes more adept over time.
Thinking through some of your Songs to see if there are parts for harmony singing could also engage him more.
I'm not sure what you might be asking of him. 
And supporting him in performance of his five Songs could show reciprocal concern for his presentation of his product.
He could play solo, his five Songs, in the 'Hot Spot', opening for you, then dropping back to let you take center stage.
I see you were wondering what to do back in March. I only recently noticed the post. Has a decision been made about continuing the duo?

@gary-e-andrews I said, it was taking him weeks to learn one song. He wanted to prevent me from playing most of my songs at the open mics, and to stay with the small number he knew. 

About a month ago, I stopped playing with him and found someone else to play with. He can easily learn my songs, and I can easily learn his. I don't have to write anything out for him, because he can hear the chord changes.

I need to play with someone who is willing and able to learn as fast as I can.

Polly.

Music in any form is like SPEED DATING. We write with multiple people, perform with multiple people, and continue to try out different combinations until we find things that work. Good thing you moved on and found someone else. The same comes to co-writing. There is no reason in this day and age to just have only one co-writer, or to be stopped from having other opportunities, solo or other wise. Most people have solos, duos, combos, as today it is an "DO EVERYTHING YOURSELF" until you either find the perfect combination or get other people to take on the job.

Very probably, the first person you worked with had his own agenda and desires, or had very little and ust didnt want you to do anything else like see other people. Time to move on and you did. Good for you.

I would second the person who mentioned NSAI to you. The best thing for any writers or performers are to be in social settings with other people who share their passions and interests. From there, a lot of things can happen. There is a formula I use that you might find helpful.

ACTIVITY+PROXIMATY=OPPORTUNITIES

If you are constantly active. Writing, performing, building relationships, getting gigs, etc. it puts you in the proximaty of other writers or interested parties. From there, you gather opportunities that will be beneficial, or in some cases, help you learn what NOT to do. Seems as though you've already experienced one of those. There will be more. You just try to have more good experiences than bad ones.

MAB