My ancestors came from western Ukraine.
Ukraine is a beautiful country, with rich soils and other natural resources that have coveted by many. Over the centuries, Ukraine has been fought over many times, by many armies. Oftentimes, Ukraine has veritably been a war zone. A war zone is rarely anyone’s first choice as a good, safe place to live.
I don't know when your friend's parents left the Ukraine, so I'll give you some western Ukrainian history in a nutshell:
Between 1387-1772, western Ukraine was under Polish occupation (while the east was held by Lithuania); in 1773, western Ukraine was turned over to the Austrians; during the winter of 1914-1915, the Tsarist Russian army occupied western Ukraine until the Austrians recaptured it; after World War I (1918) and the Russian Revolution (1917) had shattered the Austrian Empire, Ukraine had a brief glimmer of independence; in 1919, Poland took western Ukraine again; in 1920, the Soviet Red Army took western Ukraine, but allowed the Poles to continue ruling it; (in EASTERN Ukraine, the Soviet government deliberately starved millions of Ukrainians to death whilst it sold the grain they produced to other nations - see "Sources" below); in 1939, Germany invaded Poland and started World War II. From the first day of the war Ukrainians suffered because German bombs killed many Ukrainian civilians in Poland, and killed many Ukrainian boys/men forced to serve in the Polish army; later in 1939, the Russian Red Army invaded and occupied western Ukraine, and still later in 1939, western Ukraine was incorporated into the USSR.
Whilst Ukraine was ruled by Poles, Austrians and Soviets, the Ukrainian citizens were treated more or less like second class citizens. Between 1939 and 1991, the Soviet “iron curtain” prevented the citizens from leaving. Food was rationed. Mail was censored, too (e.g., lots of information was either confiscated or blacked out with thick black marker). Living inside the "iron curtain" was less than pleasant. I can certainly understand why someone might want to leave the first chance they get.
Ever since 1991, the Ukrainians have had self government, but those governments have left a lot to be desired. All those many years of Soviet occupation left a lot of damage that is very expensive to repair. For example, visitors in most of the better hotels in the Ukrainian city of Lviv usually have electricity and running water 24/7, but the citizens of Lviv suffer regular black-outs and water rationing. Basically, the living standard aren’t as good as in North America, etc. Although running water and electricity 24/7 isn't everything, I can certainly understand how someone might want to leave Ukraine, even now that it has independence. Besides, there's always the threat that their independence could be lost in the future, in yet another war.
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HERE'S AN IDEA: Why don't you ask your friend why her parents left the Ukraine? She'd probably have a better idea than anyone on "Answers", and she'd probably want to tell you.
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P.S. Your “Additional Details" don’t make sense. Of the answers you received so far, I don’t see where anyone was being a "jerk". Perhaps the “jerk” deleted his or her answer.