Perhaps a clue, in retrospect (SPOILERS)
The fact that Jackie, who describes herself as "broke" in her opening scene, can afford to stalk Linette and Simon on their glamorous trip abroad is perhaps an indication that someone is helping her achieve this.
It's possible Jackie stashed money away for her wedding truseau or something in the months leading up to the film, then decided to blow it all on this trip. Yet at the same time, it's somewhat...suspect (?)
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