He is the billionaire Google boss under fire for not doing enough to protect children from internet porn.

Yet today The Mail on Sunday can reveal that 58-year-old Eric Schmidt, Google’s executive chairman, does fiercely protect one thing: his own private life, which is as colorful and complex as the ever-changing ‘Google doodle,’ which pops up each time the search engine is launched.

In the past few years, the unlikely sex symbol with thinning hair and pockmarked skin has embarked on a string of affairs with younger women, including a vivacious television host who dubbed him ‘Dr Strangelove,’ a leggy blonde public relations executive and a sexy Vietnamese concert pianist.

Meanwhile his wife Wendy, 57, remains at one of the couple’s many homes, a $23million waterfront mansion on Nantucket Island, Massachusetts, where she focuses on her philanthropic work amid reports that she has accepted their ‘open marriage’.

Schmidt, worth an estimated $8.2 billion, is believed to have had at least one mistress sign a confidentiality agreement not to divulge any details of their relationship.

Stunning TV personality Kate Bohner, aged 46, had a three-year affair with the married mogul from 2007 to 2010.

‘As far as Kate was concerned it was true love,’ her close friend Jason Parsley, a journalist, told The Mail on Sunday. ‘She adored Eric. This wasn’t some short-term fling. This was a serious love affair that went on for three years.

‘The reason I am speaking out now is that it is ironic that someone like him can be so free and easy discussing other people’s privacy issues online while using his vast wealth to protect his own image.’

Bohner moved to Los Angeles to be near Schmidt, whose property empire includes a home near Google’s Silicon Valley HQ, and a $38 million estate in Montecito, California.

Bohner laid bare her feelings for Schmidt, whom she jokingly called ‘Dr Strangelove,’ in an online blog: Recoverygirl007. She revealed he had given her a prototype iPhone (late Apple boss Steve Jobs was a friend of Schmidt’s), whisked her away for romantic getaways and lavished her with expensive jewelery.

She wrote of her pain at their breakup, saying: ‘I’ve been sleeping with my Blackberry just in case Dr Strangelove might send an email.’

At the time of the affair, Schmidt was at the height of his power. He was brought in as Google’s CEO in 2001 by creators Sergey Brin and Larry Page, who relied on his expertise to turn their modest Internet search engine into a global media powerhouse.

But Google has been criticized for not doing more to protect users, particularly children, against the  proliferation of porn on the web.

Google, which says it has a ‘zero- tolerance’ policy on child sexual abuse content, has argued policing the billions of images, stories and data generated daily on the Internet would be a Herculean task and any controls could inadvertently restrict legitimate online searches. It says parents can use Google ‘filters’ like SafeSearch to prevent children accessing pornography.

‘What I worry about is that such  laws are often slippery slopes,’ Eric Schmidt told a conference in May 2012. ‘In many other countries, adult pornography legislation is an attempt to legislate something else.’

But a source who knows Schmidt well defended him, saying: ‘Eric is integral to the success of Google and in enabling it to become a hugely successful company that employs 35,000 people around the world and is a service that is much-loved by its users. He was a great CEO and very well regarded as someone with extraordinary technical knowledge and great business acumen.’

Bohner did not return calls or emails this week, possibly bound by her believed confidentiality agreement, but her close friend Parsley insisted: ‘It was a serious romance, at least as far as she was concerned.

‘To my knowledge he would pay for her to travel to see him. He was always promising her he would get divorced. She cried on my shoulder countless times. She believed wholeheartedly he was going to leave his wife for her.’ Schmidt and Bohner were photographed together at the Burning Man festival in 2007, a gathering in the Nevada desert which showcases art and encourages creative thinking.

The couple wore goggles and bandanas to protect themselves from sandstorms. Schmidt posed with his arm around his mistress, although he refused to join the masses camping in the desert, preferring a five-hour round trip to the nearest hotel.

Parsley continued: ‘They communicated a lot by phone and email when they were not together. But it devastated Kate that he would chose to spend holidays with his family. It was always the same, Thanksgiving, Christmas, all the big ones.

‘I am speaking out because Kate has been the victim of unfair comments online. In any affair, the woman always gets the blame – “Oh, she knew he was married.”

‘Well, in this case it’s not so cut and dried. Yes, Eric was and is married. But he needs to look at himself long and hard and start living a truthful life. Eric wants to have his cake and eat it too. He has had numerous affairs and everybody knows it.’

Like Bohner, Schmidt’s other reported girlfriends have been glamorous, successful women of a certain age.

There was Marcy Simon, a leggy blonde PR executive in her mid-40s who was spotted with him on holiday on the French Riviera in 2006 and, according to reports, remains close to him still. He gave her a large, canary-yellow diamond ring.

Website Gawker.com reported on their split in December 2007, and also alleged that the couple rekindled their relationship in 2009,  when they were reportedly spotted together at the Aspen Ideas Conference in Colorado and in California.

Schmidt was also linked to Lisa Shields a 47-year-old divorced single mother who worked as a producer for America’s top-rated breakfast show Good Morning America.

According to the New York Post, in 2011 Schmidt took her on holidays aboard his $72.3million superyacht Oasis to the Caribbean and the South of France.

They were spotted dining out in the millionaire’s playground of Southampton in upstate New York, and according to the New York Post were ‘also spending time at a summer rental in the Hamptons’.

A source told the Post at the time: ‘She has been telling friends they are dating and they have been going out openly in New York and the Hamptons as a couple.’

Shields now works as a publicist for the Council On Foreign Relations in New York, and speaking from her weekend home in the Hamptons did not deny her reported relationship with Eric Schmidt, but added: ‘I never comment on my  personal life.’