Clyde is concerned with what is right or wrong, whereas you seem to be homing in on what you can get away with. Having a close relationship with a 22 year old Chinese student will have much more and longer lasting disabling effects on her than a relationship in the west with a western student. Your average Chinese student must prepare herself for the often hard reality of a Chinese husband and way of life. I don't believe that this Romeo really exists at all but if he does he already has a wife, he's 42 and he probably won't end up marrying her. However, supposing the relationship lasts for a couple of years; that couple of years of a totally different way of life to what normally should have been her lot, may mean she will be unable to adapt herself to the type of life she has to follow in the future. While she is with our Romeo, they may holiday together, take a plane or two somewhere, when a hard sat on China rail awaits her when Romeo needs to return to his own country. When you interfere in somebody else's life, best be sure you're not taking them somewhere that they can't get back from; somewhere meaning a way of life. I can't expect to feed my cat on salmon for a year and then expect her to return to dried munchies.
You yourself would probably spoil her on expensive coffee and Ipods(or is it ipads) Yorkshire Ales and a holiday in the Dales. Just joking.