Firstly, what type of African is this? African is extremely generic, and says nothing about the fish except that it's from somewhere on the huge continent of Africa.
For now I'll run with the assumption that it's an mbuna, as they're most popular around here. Now, fish don't actually experience lonelyness, but breeding and chasing and fighting are almost all these fish do besides graze algae and search for food. To put it antropomorphically, I'd say he's more bored then lonely.
Adding one more is not the solution though - if you add one, it will be killed. Either stock up the tank with a number of them, or leave him be.
This whole point may be moot, depending what kind of fish it is, of course.
What size is the tank?
