My friend is cheating on her boyfriend in Germany. What can I do to make her stop?

Please let me know when you post this. My friend is dating a very wealthy guy. He loves her and takes care of her but she is still cheating on him. I have advised her so many times to stop cheating on him but she wouldn’t listen. This guy takes care of her. He buys her very nice gifts and cares for her so much. I don’t like the fact that her boyfriend is going out of his way to please her but all he gets in return is cheating. The annoying thing is that the guys she is cheating on him with are not even serious people nor are they doing well. 

Most times she is even the one sending them money. She gets money from her main boyfriend and sends it to these other guys. The main boyfriend sends her money and gifts frequently so she always has more than enough. He even rented an apartment for her and furnished it to her taste. He also bought a car for her last year. He is doing so much to please her and ensure she is comfortable. It saddens me that after all his efforts to make life easier for his girlfriend, she cannot do the very least which is at least to stay faithful and respect him. 

The guy stays in Germany and comes back to see her twice every year. When they spoke last month, he told her of his intentions to see her people when he returns. I thought that this was going to make her stop jumping from one man’s bed to another but it didn’t. She didn’t even see it as anything. I have asked her so many times if she likes the guy and she said she does. I really baffles me why she would cheat on someone she claims to love. I have asked her if she loves the guy enough to marry him and she still said yes. If she cannot stay faithful to him now that they are not married, is there any guarantee that she will be faithful when they marry? 

I am bothered because she is my friend and she does not realize the treasure she has. She has what a lot of girls including myself would die to have. A man who loves you and spends on you without looking back. What else can anyone ask for? The guy is very handsome and cares to a fault. He is always asking after her parents and siblings. Sometimes he sends money to her to give to her parents. Even though she is from a poor home, he doesn’t care about the class or anything. He genuinely loves her and it is so obvious. 

I don’t know what else to do. I have tried to talk sense into her head but nothing good comes from it. I want the best for her. I know that if anything goes wrong, she would never in her entire life forgive herself. This guy has made her life so much better. She is living in luxury. Even the job she has, it was through the guy’s help that she was able to get the job. Many of the good things in her life are all in one way or the other tied to this guy. I want everyone who reads this to advise me. What can I do to make her come to her senses? She has a lot to lose and I don’t want her to realize this when it’s too late. Please what can I do?