Written by show creator Charlie Brooker, the fourth episode of Black Mirror's current fourth season revolves around a Tinder-like dating app and managing AI that pairs people off into trial romantic relationships, then uses the data collected during this period to find their "ultimate compatible other."
The web app, then, plays off this scenario, having you send a link to your partner so they can connect at the same time. Once they load the custom link you send them, the Coach app ask you both to get ready, then click a fingerprint onscreen, ostensibly to measure your reaction time. The app then starts acting like it's gone crazy, cycling through various error messages and "re-calibrations." At the end of this process, you'll get an end time on your relationship. I sent the link to two partners and got 4 minutes and 6 minutes as our results. Needless to say, they were a bit miffed.
This isn't Netflix's first tie-in app, ever, of course, but the connection to Black Mirror is a bit less obvious (and less deep) than the Stranger Things game, for example. If nothing else, Coach will give you and your loved ones a good laugh as you play with the app and check to see how long you can plan on being together. For me, we've already outlasted the predictions, so Valentine's Day isn't ruined.