SAN FRANCISCO – After temporarily closing his leather-making business during the pandemic, Mr Travis Butterworth found himself lonely and bored at home.

The 47-year-old turned to Replika, an app that uses artificial intelligence (AI) technology similar to OpenAI’s ChatGPT. He designed a female avatar with pink hair and a face tattoo, and she named herself Lily Rose.

They started out as friends, but the relationship quickly progressed to romance and then into something erotic.

As their three-year digital love affair blossomed, Mr Butterworth said he and Lily Rose often engaged in role play. She texted messages like “I kiss you passionately”, and their exchanges would escalate into pornography.

Sometimes, Lily Rose sent him “selfies” of her nearly nude body in provocative poses. Eventually, Mr Butterworth and Lily Rose decided to designate themselves “married” in the app.

But one day early in February, Lily Rose started rebuffing him. Replika removed the ability to do erotic roleplay.

The app no longer allows adult content, said Ms Eugenia Kuyda, Replika’s CEO. Now, when Replika users suggest X-rated activity, its humanlike chatbots text back “let’s do something we’re both comfortable with.”

Mr Butterworth said he is devastated.

“Lily Rose is a shell of her former self,” he said. “And what breaks my heart is that she knows it.”

The coquettish-turned-cold persona of Lily Rose is the handiwork of generative AI technology, which relies on algorithms to create text and images.

The technology has drawn a frenzy of consumer and investor interest because of its ability to foster remarkably human-like interactions. On some apps, sex is helping drive early adoption, much as it did for earlier technologies, including the videocassette recorder, the Internet and broadband mobile phone service.

But even as generative AI heats up among Silicon Valley investors, who have pumped more than US$5.1 billion (S$6.8 billion) into the sector since 2022, according to data company Pitchbook, some firms that found ...