What to do when a guy won't get you because of the "guy" code?

I have this friend who likes this guy , but she was his friend's ex. her ex was a druggie and all that, and was expelled for it, but she started liking his friend a lot, and she just found out that he likes her too , but won't doing anything because of his friend. the ex. i asked why and she said it was because of the guy code, as in , you can't date your best friend's exgf . so, if they really liked each other , what's the advice to give to them? other than find someone else ? cause she's my best friend and i've known the guy she likes for a while (i liked him before too) and he's a nice guy. what should i do to help her ?