Both of them had messed up families, his brother tried to kill him for power and her mother tried to kill her because she couldn't handle having a child of incest any longer. Perhaps that was one of the reasons they were attracted to each other, being screwed over in the healthy family department tended to leave you emotionally damaged. She had no idea what a healthy couple was supposed to act and be like, save for what she saw in the movies and read in her romance novels, and the closest he came to a healthy relationship with a woman, that wasn't platonic, involved wearing a condom when he screwed them.
That is why they were winging their relationship. They are doing the best they can, despite the fact that their relationship as a small chance to actually work out. But that don't care that their families screwed them over for the most part or that the chance of their relationship succeeding is none existent all they care about is that they are in fact trying. Tomorrow the entire thing could blow up in their faces, but that is tomorrow and they will deal with it then, this is now and they are enjoying their now.