To be completely honest, the overwhelmingly majority of Muslims in the west don’t actually understand what being religious means. Their understanding of the Dīn is extremely superficial, and they have tons of extremely problematic ideas that go against core tenants of Islam. Their morality and beliefs are more in line with liberalism, secularism, the UN, and international law than they are with Islām.

And more often than not, when someone from the diaspora wants to marry outside their culture or ethnicity (and I’ve noticed this is particularly common with women), it is usually because of exposure to some form of the media or social influence. I am not making a blanket statement here, but if you investigate a bit further, you’ll realize that a lot of these people become infatuated with a specific culture or race due to TV, social media, and/or influence from their friends. This is especially common in the west, but you find this everywhere these days. The term people like to use for this is “fetishization” but I prefer to avoid using terms that are often abused in leftist circles. 

Also, not all negative attitudes towards certain races or cultures is “prejudice”. Prejudice would be preconceived notions that are not based in reality (there are a lot of parallels between actual prejudice and the “fetishization”). Although cases like this exist, it definitely isn’t as common as people make it seem. A negative perception towards a particular race or culture can be justified or understandable, just like many stereotypes have elements of truth to them. 

The Culture vs Religion debate (i.e., “this particular practice or ruling is not from the Dīn, it is actually from culture!”) is another very abused talking point, and it is hardly ever applied correctly or truthfully nowadays. More often than not (especially with the popular issues most people today complain about due to the widespread cancer of individualism), you’ll find that the cultural practice or norm is in fact either directly from the Dīn and can be found in the books of fiqh, or the practice is not an established decisive ruling but is very much in line with Islamic ethics. But because western “scholars” have been lying and distorting to appease diaspora and westerners, the laypeople have become confused. They don’t actually know how to differentiate between what is from Dīn and what is from culture. If they don’t like something, they’ll say “it’s just cultural”. If their culture doesn’t allow something they want, they’ll claim “the Dīn supports it though!”.

Sometimes the parents are being totally unreasonable. Most parents today are genuinely clueless about what ideas their children hold. But sometimes the parents are quite wise and see through these things. There are many variables that one must take into account. Hence, every situation should be analyzed in detail.