This is all good and easily said, when that's the problem. But quite often, I think that's not the case.
At my last church, there was a strong single's ministry, people were volunteering to teach, serve, etc. But, the church decided to do away with the single's ministry, because they didn't see the need for it. Instead, single's Sunday school classes ended up being mixed classes. Supposedly all of the Sunday School classes were suppose to be for married and singles, but I don't think that really happened. Instead, the married classes mainly stayed classes for marrieds, while the Single's classes became mixed. At least, from what I saw. Many of the single's left the church because they felt like the church refused to see their needs. It wasn't until a major corporation came in, not to mention seeing the changes in the culture did the church realize that maybe there were more single's then they realized.