The survey, by market research company Ipsos, found that married Indians - more than singles - look to their sex lives for happiness.
Having a good sex life provides the greatest happiness to 44 percent of Indians (those who are married or are living with their partners), whereas the figure is 34 percent for singles.
Two-thirds (65 percent) of Indians who are married or in a domestic partnership think their relationship gives them the greatest happiness.
"Love and loyalty are in the air this Valentine's Day. In India, it is common to see millions of couples living with the same partner till the end. Marriage is a strong bond and it is considered sacred and they are far more successful compared to many other countries," Ispos' India head of marketing communication Biswarup Banerjee said.
"Thus, it is no surprise that majority of Indians find the greatest happiness being with their partner or spouse," he said.
Globally, nearly two-thirds (63 percent) say their relationship with their partner or spouse gives them the greatest happiness. Of the 41 percent who are not married or in domestic partnership, almost half (45 percent) say finding someone to be with would give them the greatest happiness.
Globally, having a good sex life provides the greatest happiness for 38 percent of those who are married or living with their partners and for 34 percent of those who are not.
The greatest proportions of those in committed relationships who say their partner gives them greatest happiness are found in South Africa (82 percent), Turkey (80 percent) and Mexico (79 percent).
Ipsos interviewed 21,248 people in the age group of 16-64 years in 23 countries from Dec 6-19, 2011. Of those, 59 percent (12,627) are married or in domestic partnerships and 41 percent (8,621) are not.