Four out of 10 Americans say they don't need a marriage certificate to prove love or commitment, according to a new online survey.

Overall, 44 per cent of the 7,113 Americans aged 20 to 69 who took part in the poll by Zogby International and AOL Personals said they didn't need marriage to validate their relationships.

"People are coming online to find that special someone but that special someone doesn't necessarily translate into a marriage, and more so with the folks in their 60s." AOL Personals Director Keith Brengle said.

Half the respondents between the ages 20 and 29 said marriage wasn't necessary.

A majority of respondents also said they would prefer to live together first before marriage and most said marriage should truly be until "death do us part," especially those in their 30s (73 per cent).

Trust was ranked highly important to most singles polled, especially for those in their 20s.

Although 20-somethings said they were more open to experimenting with sexual relationships, they were also more willing to end a partnership over infidelity when compared to respondents in their 50s and 60s.

"Trust is still extremely important for the 20-somethings - they wouldn't work through any infidelities, they'd walk away," Brengle said.

However, older respondents were more interested in companionship, didn't feel the need to be married and were more comfortable accepting infidelity "as a part of life."

"They've probably been tested so they're much more accepting of things that traditionally you would think they wouldn't be," Brengle said.

"As such they're going to be less likely to have to snoop through a partner's things to try to find indiscretions."

The survey also found that as people age they are more likely to believe that more than one soulmate exists.