Loupe itself can see if you have tinder/bumble/hinge installed (verify for yourself: install tinder, then install loupe, don't give it any permissions, and it can tell if you have tinder installed or not). So the answer is: buy the data from any app your partner has installed! Or more easily, a data aggregator which will have already combined data from hundreds/thousands of apps.

So your partner only needs to have had 1 single app from the list that sells user data to a data aggregator for this to work. They do not need to have installed some special app.

Here's a random Slate article about apps getting your data and selling it to aggregators/brokers, who sell it to third-parties (you, or I, could be one of those third parties).

> How Shady Companies Guess Your Religion, Sexual Orientation, and Mental Health And sell that data to the highest bidder.

https://slate.com/technology/2023/04/data-broker-inference-p...

It already happens all the time. It even has a name.

https://en.wikipedia.org/wiki/Stalkerware