re: Most red dwarfs are single, are they not ? And they are the most numerous
I don't think most red dwarfs are necessarily single. I imagine the percentage is about the same as for any other other star. However, red dwarfs are extremely long lived, so for old ones, their companions have probably already evolved off the main sequence and either supernovaed or are white dwarfs now. Proxima Centauri, is a member of the Alpha Centauri system, and it's a red dwarf. For close binaries, if one rapidly swells to fill its Roche lobe, the more massive on may just suck all the matter out of the other, or the stars otherwise merge.