Im sorry to hear this story there is a low value people put on another person. It sounds like a narrow minded sex tourist just making things to suit them and their holiday. There are a lot of good guys out there as there are Pinays, but scammers on both sides look to make things difficult. I wish your friend all the best in finding someone who values her as she deserves. No person should be treated this way.
How to make sure the guy is true is impossible. If you look at assault cases in the U.S. on Pinays its very high from husbands and the majority put up with it because of their kind nature and the fact of trying to satisfy their husbands needs. These types of guys are just predators and hard to detect and only advice I would give is trying to find a guy via your other halfs friends etc. Like me I would take personal responsibility of your friends care if I said my friend was a good match etc. Only advice i would say is be very careful. Its like a lottery on good and bad.