Put "" around "white" and "Asian", please.
"these characters fuelled the imagination of Asian girls about how white men should be better boy friends and lovers than Asian men."
I think there is something else going on. In the Hollywood movies (especially the older ones), the "white" male leads are typically paired with "white" female leads. I suspect the real reason (possibly subconscious) why "non-white" female Eurocentrists want to have a "white" boyfriend is because they want to fulfill their actual fantasy, which is for themselves to
be "white" women. This is related to:
https://trueleft.createaforum.com/human-evolution/mate-choice-copying/at being with a woman — particularly a beautiful one thought to be the significant other — does increase a man’s appeal in the minds of female evaluators.
...
the studies that varied the beauty of the female partner found that making her more attractive also increased his score.
If "non-white" female Eurocentrists are shown a "white" man with a "white" girlfriend and a "white" man with a "non-white" girlfriend, which one do you think will get the bigger score buff? Which girlfriend would they rather fantasize about being? I suspect we all already know the answer.
"when one girl in a social group is known or seen to have successfully captured a star-looking sort of white guy, it became an instant boost for either the confidence or envy of other girls tin the group to raise hope in getting one for themselves. To satisfy their craving, they are consciously or sub-consciously willing to drop their standard eventually to the state of "any white guy would do". This entails a vicious loop in itself, making even the most ordinary white guys more pompous and in demand."
This further reinforces my theory. In their minds, it is not even about the quality of the particular "white" guy. The "white" guy is just a prop to help themselves pretend they themselves are "white" while with him.
The best way to break a vicious loop is to superimpose a different feedback loop. For example, if the first girl who gets a "white" boyfriend is heavily ridiculed as a Eurocentrist by the rest of the social group instead, that could interrupt what you describe. This could even be done pre-emptively: for example, if the rest of the group sees one of their members being Eurocentrist in other ways, they could already start ridiculing her as someone likely to
try to get a "white" boyfriend. The aim is to make it so that no one wants to be the butt of these jokes.