(US) HELP is my sister getting romance scammed?

A 25-year-old woman met a Dominican man on Hinge, but raised concerns about his suspicious behavior, including claiming ignorance of her U.S. origin despite no location changes. She has been in daily contact with him for months, and despite red flags, she plans to visit him alone in the Dominican Republic in August. Her family fears she may be a victim of a romance scam or dangerous situation.