In the base version of Roommates, the character you normally can't romance will have a label over their face in the status screen that says you can't romance them. For example, if you're playing as Max, Dominic's face will be obscured, while if you're playing as Anne, Sally's face will be obscured. I purposefully went and removed these for the purposes of the mod, though, so if the mod is working properly, when you go and check the characters' affections, Dominic's/Sally's face should be visible. If that's the case, you'll know it's working just fine :)