So the idea is that actors sign up for We Got Married and become "married" in the show. They share a house, go on dates, and do all sorts of cute couple things like going on trips together. However this is all on the show. They do promise not to be dating others while on the show and they also are often asked questions about each other on talk shows, other variety shows, etc. Couples usually stay in touch, but they don't have relationships after the show. At the end of the season/ their relationship they take wedding photos together. Which is super cute :) Last but not least, the show is scripted! Hope that helps :)
[Disclaimer I have only watched 20 or so episodes, so I am, in no way, an expert. But my friend is a WGM junkie so I learn a lot from her!]