>>94316864True, but the difference between the two is that Oskar and Star never dated. Oskar only showed interest in Star AFTER she lost interest in him. What's worse, it's actually shown why Oskar is a bad choice for Star inherently; he has serious family issues and needs constant validation.
Jackie and Marco, even if they haven't been explored a lot, have been a couple since Bon Bon and, despite whatever the priorities of each person are, they DO both like each other. Whether that's enough? Probably not, but the relationship has the potential to not be toxic if Marco put in the effort.
Since he is not putting in effort but Jackie is, in the context of preserving the relationship she is in the right, and she has reason to be upset. Thus she has enough of a reason to get some amount of focus on her, even if it's small.
