People should marry whoever they want. There is nothing wrong with that. Its only wrong when its done for the wrong reasons (Aka visa's, passports, greencards, etc etc.)
However, there may be some cultural obstacles they might encounter,I personally know many non-Polish and even non-European men who married European women and have had successfull marriages.
On a slightly different note; I think if a Muslim (Arab or Pakistani) wishes to marry a Polish/European girl, it may not be for greencard purposes. In the Middle East, the men love European girls--especially Poles and Russians. There is something about them that attracts the Middle Eastern men--I can see why, European girls are beautiful :) ! Point is, its not always the reason to obtain citizenship or whatever. Sometimes its just because they're inlove with European women.
However, there may be some cultural obstacles they might encounter,I personally know many non-Polish and even non-European men who married European women and have had successfull marriages.
On a slightly different note; I think if a Muslim (Arab or Pakistani) wishes to marry a Polish/European girl, it may not be for greencard purposes. In the Middle East, the men love European girls--especially Poles and Russians. There is something about them that attracts the Middle Eastern men--I can see why, European girls are beautiful :) ! Point is, its not always the reason to obtain citizenship or whatever. Sometimes its just because they're inlove with European women.