According to the marketing chief officer, the reason why Primera Air has ordered A321Neo is to occupy the market while the 737Max9 was not available.
They indeed increased recently the orders up to 20 b737 Max 9 ER to use them on long range most probably on the same routes as the current A321Neo.
So within 2 years Airbus fleet will be probably disappeared from the Primera fleet and be replaced by a single b737 fleet.
The only question is that : why did they order only 2 A321LR?