All girls irrespective of which country love to be with their own people. Mainly they identify the culture, gossips of interest, behavior etc.
Even if a foreigner marries a local girl and lives with her in her country the tendency of these girls to stray is very much in the picture. Even if the guy takes her to his country she will quickly try to make friends with her own kind.
Now whether she stray from relationship or not is a different picture. If the girl is young and marries a guy who is old enough to be her grandfather it is a problem. There are plenty of inter racial and inter country marriages which seemingly have worked. But these are generally in the same age group. If the girl marries for money it is a big problem.
Now about Phi girls, many seem to enjoy being married to a foreign guy and live in Phi. It is kind of a status symbol for her and also she is well taken care of instead of slogging like other girls day to day. Girls working in AC bars comes to mind. They fight even for the 20 peso bill thrown at them.