Definition of kabureru
かぶれる (kabureru) means “be overly influenced by new ideas, especially a culture of a certain foreign country”. Similarly, people who overly advocate a certain country outside of their country are called “~ かぶれ”, e.g. “アメリカかぶれ (America かぶれ)”, that is “American-phile people”, who are overly influenced by the American culture. Ironically, however, many of them actually have a very shallow understanding of the culture/country, and often possess highly biased and overly generalised thoughts, such as “American people are very positive and enjoy their life, but people in our country are always depressed and gloomy”!
Although not used among the Japanese, you may also say “日本かぶれ (Japan かぶれ)” to indicate a “weeaboo” or a person who is obsessed with the Japanese culture.
Since he studied in the U.K., he has been really かぶれてる (overly affected by the British culture).
People who eat beef are 西洋かぶれ (overly affected by the western cultures; western-phile).
(Note): It is said that this idea used to be very common in Japan at the beginning of the Meiji era, 1800s.