Looking at an iPhone
56% of Britons believe a modern sign of true love is knowing their partner's phone PIN or Facebook passwordReuters

Valentine's Day may still be dominated by red roses and chocolates, but now the real sign of true love is knowing the PIN to your partner's phone.

More than half (56%) of UK adults believe that sharing their PIN or social media password with a partner is a modern sign of true love and a committed relationship - but it isn't all good news, as 40% of adults in a relationship regularly look at their significant other's phone behind their back.

A study commissioned by Samsung revealed that women (44%) are more likely to snoop on their partner's phone than men (36%), and on average suspicious Britons check their other half's phone twice a week for questionable texts, emails and internet searches.

Of the 2,000 respondents who took part in the survey, 34% admitted to knowing their partner's PIN, 39% know their email account password, and 26% know their Facebook password.

Six in 10 respondents said their had caught their partner cheating on them, or talking to someone they shouldn't be, while snooping on them. Over a third said spying on their partner's phone had scuppered a romantic surprise planned for them.

The survey also found that more than 40% of snoops have been caught in the act by their partner.

Text messages are most likely to be checked, followed by call history, Facebook private messages, emails and the phone's photo gallery. Internet search history and Twitter conversations are also among the most popular searches made by a snoop riffling through their partner's phone.

With 60% saying they had found something inappropriate, 32% said they would confess to their snooping if it meant they could confront their partner about what they'd found.

Almost a fifth said they would think up a way of bringing up what they'd found without admitting to how they'd found it - and the same number would break up with their partner immediately after finding inappropriate messages. However, 17% said they would keep quiet and try and forget what they'd found.

But snooping through a partner's phone can end in disaster. Four in 10 said they'd be angry if they found they'd been spied on, while 24% said they would end the relationship there and then.