Why is she listening to this prophet - just out of interest?
I don't believe a prophet of God would prophesy about someone's personal life to that degree. If they were truly concerned about God's glory, they might say something like "it is not God's will for you to marry an unbeliever", but I don't believe they'd say "God says that you have to marry this man".
I can't help thinking that, as he has got her money, either he feels he needs to give her her money's worth so she can't complain later, or he is keeping up the relationship so that she might give him some more.
You can't make people see what they don't want to see, but at this rate, this woman will either go broke, have a breakdown or both.