Dating system: each time a new game
Each time you date a character in the game, beginning with Rita in the upcoming update "Ice Dream", you can choose to bring them to a place you already discovered while exploring the city.
You won't know if the date will go well or not, because that depends on fate (and your choices and comfort level of the other one). The more you build up your date's confidence the more chance of success you will have.
Each character you date will have a pool of 50 different characteristics (i.e. people they like/dislike, favourite foods, informations about their family or job etc.). You'll randomly get to know a different characteristic each time a date will go well and, since they're random, they will be different each time you play General Practitioner or load a save game.
When you reach a predetermined amount of infos (and then you need to date that person more than once to get all, that also means that each game you won't discover all fifty), the relationship will grow to a new step where your date will ask you (in a different way according to her character) if you really know her so well or if you're just using them. You will need to answer up to 10 questions regarding informations you received while dating. If you answer 5 of them correctly you'll progress in your relationship... if you fail at least 5 of them your date will leave you for good and you won't be able to progress their romance further.
Each date's outcome can be also influenced by what you already know (or don't) about her tastes. For example you could learn Rita doesn't like horror movies, so choosing one for your movie theater's date won't be the right choice.
Imagine the full game, as I am doing. In the full game you can date dozens of different people, each one with her own agenda and interests from a pool of 50. Since you can date just one each day you will need many hours to date everyone and you need to remember what turns them on or off (like you would do in real life). This way the game will be challenging enough without becoming frustrating and each playthrough will be different so you won't know what to expect.