In my point of view, i find that it is really how the singles themselves look at it.
Many singles are happy at this state as they find that there are lots of advantages being single. One of the main enjoyment of being single is freedom, as singles will have less commitments and much more time compared to people in relationships or even married. The time and freedom that they get all allow them to soar in their careers as they could focus on their work. This is something that people who are married or in realtionships not able to achieve as they had to spilt their time for family. Thus this freedom that they have have allows them to do alot of things that they dream of doing, for example going for further studies or even simple things like spending time with friends and families. Many people who got married or even in relationship had lesser time with family and friends due to their committments towards the new realtionship or family.
However there are still some singles unhappy as they find that this is not what they want to achieve in life. Not all the people in the world wants to soar in their careers, some just want to live a simple life and wish to find the right partner and settle down. They feel that the happiness that they are finding is they joy of living together with the one whom they love or even to the extent of giving birth to a child of their own. These emotional pleasures are feelings that singles can never get. Therefore they these singles are unhappy as they could not find the happiness that they want.
In conclusion, singles have to look into what do they want to achieve in their lives, in another words what are their priorities in their lives? This then will determine whether they will be happy about being singles.
-Vivian =P (there may be spelling and grammer mistakes!)