Good question. In my case, my first cat (an only cat) was sort of an experiment because I had never had a cat before, so I thought it was smarter to go with one. Then, when we lost her 2.5 years later, I did some soul searching and realized I really just want one cat. I doted so much on her that I couldn't imagine having the time or energy to dote on two! So we adopted Murphy, who was labeled a "must be an only cat" at the SPCA, and he's been an only child since then . . . which he loves.
Holly and Murphy