She's an adult so I don't see a problem there, technically. A question: Is she fluent in English--have you actually spoken to her? If you do the trip, please use protection...I wouldn't take her word that she's "on the pill," etc.

I know a Russian woman that came to the US via marrying a US citizen. They divorced but liked the arrangement at the time. The woman I know has a "side business" translating and writing letters for Russian women that want to marry a US citizen.

Good luck whatever you decide and keep us posted.