If people are interested in Russian or Ukrainian women, there are protocols to be followed. Search the net for them. There's also sites that list known Russian and Ukrainian scammers.....he was not performing 'due diligence' on his own behalf if he was caught up in it.
Never send money to them if they're asking for passport or flight and travel money, chances are one will never see it again. Or they will be asked for more. lol....As PT Barnum said, this way to the egress....I mean a sucker is born every minute.
Advice has it that one should visit the person, woman, in their country and spend some time with them before accepting them into their lives. Who knows what kind of psychotic nutbags one might lovingly welcome at the airport? Even if they show up, there's other scams, like being married for two or three years then taking half the guys property.