Poor Opal seems eternally frazzled and upset in What Happened to Goodbye. That's because she's the manager of Luna Blu, the restaurant that Mclean's dad has been brought in to fix, and she's not happy with someone coming in and telling her what to do. Mclean even catches her outside talking smack about her dad:
"I mean, it takes serious nerve to just come in here and call yourself an expert on any and all things," she was saying. "Oh, and you can just tell he's used to women falling all over him and agreeing to everything he says, even when it's stupid bordering on offensive." (2.71)
Even though she and Mclean's dad don't get along at first, it soon becomes clear that Opal has a completely different perspective on the restaurant—and it's not a wrong perspective to have. She sees it as a place for the community, and values the people who come in and the people who work there. She's also the person who oversees all of the model town building—yup, this lady's all about bringing people together and fostering connection.
With her help, Mclean's dad starts to see that the restaurant business is made up of more than the bottom line. She also thaws his cold exterior and ends up being the first girlfriend that he dates without running out on—and that's quite an accomplishment.
By the end, Opal steps in to offer Mclean a place to stay so that she can finish out the rest of high school in Lakeview. She understands how important it is for Mclean to be a part of this community, and she doesn't want to take that away from her—so while Mclean's parents allow her to stay, it’s Opal who ultimately makes this possible for our main girl.