I'm afraid I don't see your point. You asked:

> how do you believe someone loves you and is going to marry you without seeing them?

How does one believe that? Well, they choose to. It might very well be irrational, it might be outlandish, yet they still choose to believe it. People choose to believe all sorts of outlandish things all the time. Sometimes they were right after all, sometimes not. Given that this instance perfectly fits established patterns of scams I think it's a perfectly fair assumption that this is a scam until proven otherwise.