Defamation (libel and slander) consists of false statements (or direct implications) of fact. Actionable defamation consists either of those false claims that cause quantifiable damages, or that claim things that are per se considered damaging --- a specific and limited list.

"This guy is a creeper and treats romantic partners terribly" is pure opinion, and cannot be defamatory. The (rare) kinds of opinion statements that can be defamatory generally take the form of "I believe (subjective thing) about this person because I observed (objective thing)", where "(objective thing)" is itself false. "The vibe I get about this person is that they hunt humans for sport" does not take that form and is almost certainly not defamatory.

Under US law, providers are generally not liable for defamatory content generated by users unless you can show they materially encouraged that content in its specifics, which is a high bar app providers are unlikely to clear.

> or that claim things that are per se considered damaging --- a specific and limited list

Standard disclaimer that law varies by jurisdiction. However, that limited list typically includes claims that the person committed a crime. Many juristictions also include accusing someone of having a contagious disease, engaging in sexual misconduct, or engaging is misconduct that is inconsistent with proper conduct in their profession.

In other words, the types of things I would expect people to be talking about on tea overlap heavily with defamation per-se.

If the users were careful to make all of their statements opinions, that defense would work. However, I doubt that is the case. Instead, I expect many users to include example of what their ex did that led to their opinion; which gets directly into the realm of factual statements.

The provider protections are real, and likely protect the app from direct lawsuits (or, at least from losing them), but do not protect the app's users. A few news stories about an abusive ex going after their former partner based on what they posted in the app could be enough to scare users away. You don't even need to win the lawsuit if your goal is to harass the other person.

> "This guy is a creeper and treats romantic partners terribly" is pure opinion, and cannot be defamatory.

That is true. But i think untrained and emotionaly involved individuals will have trouble navigating the boundaries of defamation. Instead of writing opinions like “treats romantic partners terribly” they will write statements purporting facts like “this creep lured me to his house, raped me, and gave me the clap”. This is not an opinion but three individually provable statements of facts. Plus the third would be considered “defamation per se” in most jurisdictions if it were false. (The false allegation that someone has an STD is considered so loathsome that in most places the person wouldn’t need to prove damages.)

Unles specifically coached people would write this second way. Both because it is rethoricaly more powerfull, but also because they would report on their own personal experience. To be able to say “treats romantic partners terribly” they would need to canvas multiple former partners and then put their emotionaly charged stories into calm terms. That requires a lot of work. While the kind of message i’m suggesting only requires the commenter to report things they personaly know about. And in an emotionaly charged situation, like a breakup, people would be more likely to exagarate in their descriptions, making defamatory claims more likely.

> Under US law, providers are generally not liable for defamatory content generated by users…

This is true, and i believe this is the real key. Even if the commenters would be liable, the site themselves would be unlikely to become liable with them.

I wonder if you would make the same comment if the genders were reversed.

"Cofee App" for males only, that allows them to post pictures of woman they have dated, rate them and include green/red flags.

"She is not good enough in bed", "She is too fat", "She has a high body count",..

Arguing over the legal definition of the word "Defamation" is missing the forest for the trees.

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But you can ruin a person’s life on a whim. That cannot be allowed.