The Motivation is Money. Do Not send money. Suppose you get serious with a woman who lives in a country where she can easily get a tourist visa to visit you. Buy her tickets on a no-refund basis and have her pick them up at the airline office. Simple rule - any time a woman asks you for a substantial amount of money you should refuse, without exception, until you really know her well.
Family is very strong, particularly in Asian countries.
So be aware of that. Be careful of any woman who portrays herself as a victim of any kind. These are the ones to simply drop. Many scam artists will portray themselves as a victim to divert your suspicion from the scam. Whether or not she's really a victim isn't important.