They do say that 'the grass is always greener on the other side of the fence'. People who are single often want a long-term relationship... and sometimes the other way around.
Can't say much more without knowing why you ask. A relationship needs to be good for both people. There's a romantic idea that it somehow magically makes everything in your life wonderful, which obviously isn't true. The best relationships work as a friendly team (or so I hear).
