In the study, they used "aggregate, de-identified data from a sample of about 160,000 people in the United States who shared photos of cats or dogs (or both) on Facebook." From that data, they began to suss out the differences between the two groups. Outside of relationship status, they also found that dog people average 26 more friends on Facebook than cat people, further confirming stereotypes about pet owners.
However, cat people are more likely to be invited to events on the social media platform. They're also more likely to "like" indoor activities such as books, TV, and movies. They note that cat people are "especially fond of fantasy, sci-fi, and anime, while dog people like love stories and things about, well, dogs."