What to do if your girlfriend muslim?

friend of mine found nice girl, she turkish (21y.o.), he is Ukrainian(26 y.o.), she says what sex after marriage, he don’t want to marry her, just dating, but sex in that age in necessary. She study in Ukraine where people open for sex, maybe found another one, but he said what he fall in love with her.. but in that time its easy to run away.. please people help my friend

Rio Bride