Imagine this: you’ve “dated” 600 people in San Fransisco without having typed a word to any of them. Instead, a busy little bot has completed the mindless ‘getting-to-know-you’ chatter on your behalf, and has told you which people you should actually get off the couch to meet.
The memes are becoming real. 
This is just the matching algorithm OK Cupid and older dating sites used to. “The AI went on 600 dates” is just some marketing bullshit. They aren’t going to sim anything, just give people the top 3 percentage matches and pretend it’s better because the AI did it.
Yours is the realistic answer but give me the lathe for a second. If they were going to actually simulate dates and have any insinuation of it being meaningful they could probably claim they need access to all of your text messages and chats to teach the AI your voice and personality. It would be an excuse for a phenomenal level of data mining. If it didn’t turn everyone off with its overreach.
they’ll probably take information representing some aggregation of interactions for a user and make some scoring model that tries to learn from pairs of user data and outcomes (in terms of whether they successfully dated or whatever you do on these apps). 100% marketing bullshit, doing LLM inference for something like this would have costs spiral out of control FAST. But a scoring model is cheap, they have the data to make one, and it isn’t really all that innovative either.