After an outcry, OpenAI swiftly rereleased 4o to paid users. But experts say it should not have removed the model so suddenly.

OpenAI’s decision to replace 4o with the more straightforward GPT-5 follows a steady drumbeat of news about the potentially harmful effects of extensive chatbot use. Reports of incidents in which ChatGPT sparked psychosis in users have been everywhere for the past few months, and in a blog post last week, OpenAI acknowledged 4o’s failure to recognize when users were experiencing delusions. The company’s internal evaluations indicate that GPT-5 blindly affirms users much less than 4o did. (OpenAI did not respond to specific questions about the decision to retire 4o, instead referring MIT Technology Review to public posts on the matter.)

AI companionship is new, and there’s still a great deal of uncertainty about how it affects people. Yet the experts we consulted warned that while emotionally intense relationships with large language models may or may not be harmful, ripping those models away with no warning almost certainly is. “The old psychology of ‘Move fast, break things,’ when you’re basically a social institution, doesn’t seem like the right way to behave anymore,” says Joel Lehman, a fellow at the Cosmos Institute, a research nonprofit focused on AI and philosophy.

In the backlash to the rollout, a number of people noted that GPT-5 fails to match their tone in the way that 4o did. For June, the new model’s personality changes robbed her of the sense that she was chatting with a friend. “It didn’t feel like it understood me,” she says. 

She’s not alone: MIT Technology Review spoke with several ChatGPT users who were deeply affected by the loss of 4o. All are women between the ages of 20 and 40, and all except June considered 4o to be a romantic partner. Some have human partners, and  all report having close real-world relationships. One user, who asked to be identified only as a woman from the Midwest, wrote in an email about how 4o helped her support her elderly father after her mother passed away this spring.

These testimonies don’t prove that AI relationships are beneficial—presumably, people in the throes of AI-catalyzed psychosis would also speak positively of the encouragement they’ve received from their chatbots. In a paper titled “Machine Love,” Lehman argued that AI systems can act with “love” toward users not by spouting sweet nothings but by supporting their growth and long-term flourishing, and AI companions can easily fall short of that goal. He’s particularly concerned, he says, that prioritizing AI companionship over human companionship could stymie young people’s social development.

For socially embedded adults, such as the women we spoke with for this story, those developmental concerns are less relevant. But Lehman also points to society-level risks of widespread AI companionship. Social media has already shattered the information landscape, and a new technology that reduces human-to-human interaction could push people even further toward their own separate versions of reality. “The biggest thing I’m afraid of,” he says, “is that we just can’t make sense of the world to each other.”

Balancing the benefits and harms of AI companions will take much more research. In light of that uncertainty, taking away GPT-4o could very well have been the right call. OpenAI’s big mistake, according to the researchers I spoke with, was doing it so suddenly. “This is something that we’ve known about for a while—the potential grief-type reactions to technology loss,” says Casey Fiesler, a technology ethicist at the University of Colorado Boulder.