Find someone else. Honestly.
One of my best buds back in high school was a guitarist, and me and him used to jam to all kinds of music. Eventually he got really into progressive music, and he started emulating guys like Patrucci and Vai. I kept trying to jam with him for about two years, but it was becoming really dull for me. The stuff he wanted to play was super intricate and fun for a guitarist, but it often required me to play a lot of root note stuff.
It eventually got to the point where I simply stopped returning his calls whenever he would ask me to jam. I never told him flat out that I didn't like the music he was wanting to do, although I did drop a lot of hints. I would tell him at every jam that I was hoping we could start playing some of the old tunes again (lots of STP, AIC, GNR, SG, etc...).
The kicker - me and him met up at a party about a year after we stopped playing together, got hammered, and then had a long discussion about how we moved apart from each other musically and that neither of us was enjoying those jams back then. We just did it out of loyalty to each other. It was actually kind of touching in a weird way, but it also made me realize that we can't change who people are and sometimes it's best to just let them be and move on.