Don’t get attached. For 98% of you, this will happen. At the end, you will be heartbroken. Remember, you are not his girlfriend; that role is taken. And you can get left very easily if you act up. At the end of the day, ask yourself: "What benefit do I get from this?" You can either be a) the one who wants him and is trying to take him from his girl, b) the one who is benefiting some other way, e.g. financially, or c) the one who is fine with it because she has nothing else going on anyway.