Vueling, the largest airline in Spain is actually shifting from the 320 to an all Boeing 737 MAX fleet in the coming years. I was really sad to hear that given it's size and presence in Europe.
Some MBA types might also see the opportunity to lay off experienced expensive Airbus pilots and hire new cheaper Boeing pilots, classic strategic gambling, not sure those things ever pay off.
EDIT: after researching a bit more, it looks like the initial order was from 2023 (https://simpleflying.com/lufthansa-40-boeing-737-max-40-airb...), so "cozying up to Trump" was probably not a factor at the time. Also, I imagine that order being passed around like the proverbial hot potato between all the airlines in Lufthansa group, until it finally landed in Eurowings' lap: "Interested in some brand new state of the art 737 MAXes? No? Why? What do you mean, `You take them if you're so fond of them`? We would, gladly, but we have an all-A320 fleet and would like to keep it that way. Oh, you too, really?".
It's likely this. Airbus has a backlog of ~7500 A32x orders right now, and produces about 75 a month, so if you order one today, you're looking at eight years.
Though also some budget airlines like the 737 because it's _short_; it's not as high off the ground as an A320, making access via airstairs more feasible.
(They do, however, use Dublin airport's worst 'gate', 335, which is _actually_ a bus to a small fake terminal separate from any of the main ones.)
Gate 335...I've experienced it hah