> Tinder doesn’t know if they were successful or not. They just know you stopped opening the app.

Great point, Tinder has to train on data where they don't know the target variable (whether a match was ultimately successful or not).

Here's a bet I make with zero knowledge on the topic: I bet tinder could get that info (i.e. whether a user is married or not) from data brokers for 99% of users, and probably trivially.