They were almost certainly a couple who saw an opportunity to get a free apartment for a while. There have been other examples in RLC before this. Young people tend to think that living together is simple, after all they are a couple already. It's usually not simple. Things that usually are just a little annoying becomes huge after a while, and you find out things about your partner that you didn't know, just because you are so much closer now for a longer period of time (in the case of RLC, it's basically always). Hopefully they can figure things out before it goes too far.