>>89810032>Janna doesnt really like Marco doesnt she?Artists confirmed she's a monster half-breed. And in Mewnie, monsters are an oppressed minority that are starved by the Mewnie royal family.
So it's pretty obvious that Jackie's feigning interest in Marco to get revenge on Star, especially via that look she gives when they were skateboarding together.
As for Janna, she had a crush on Marco in season 1, but it became a dropped plot point for season 2. Now she's completely disinterested in Marco romantically (when he comes down the stairs in his stud outfit, she shows no interest at all; the writers way of showing they've discarded the plot point, to say nothing of her not identifying Marco as her crush in the truth or dare episode).
Basically, the writers are clearing the playing field so Marco only has one romantic option available.