Is a guy that my best friend rejected fair game?

So me and my best friend met this guy a little while back and we were going out with him and his friends pretty frequently and he was pretty clear about the fact that he liked my best friend but she was in a relationship with someone else at the time but she did tell me once that she’s starting to like him too. But with time even though her relationship kind of ended she started complaining about how needy and clingy he is and that she hates that and that he’s annoying and she doesn’t like him anymore and she just wants him to leave her alone and after she told him that honestly he did take step back and now she is trying to work out things with her ex because they still love each other and wanna get back together. And now she traveled for a couple weeks to see her family and I’m mostly alone because I’m new in this country and I know very few people so I have been going out with this guy that liked her and his friend most days and we just kind of clicked and last night he came out and told me that he likes me and wants to see where it goes and want to be with me and honestly I like him too but I don’t wanna be breaking any girl code. So what do you guys think?