I don't think you should ask the guy as that would be mean to even think of it. As a friend, you should not be thinking that and you should know that it is not cool and he is definitely off limits. I don't think you would feel good if your friend did the same and you should simply respect what they have.
You have to think about is this boy worth loosing your friend? Is she the type to hold grudges and not talk to you anymore for such a thing. But, if he liked you and it was obvious that he did why did he go to her and not you? Just some questions to think about. In my opinion I would wait. See how things go. see if she really likes him and see if he likes her as well. Now if you see that for some reason you see he has no interest in her talk to him first , just talk to find out if he likes you and what are the best steps in telling your friend so she doesn't feel hurt or feel like you did her dirty. It seems like you do care for her since your asking help on a question of the sort of question like this because if you didn't you would just have talked to him by now. So just see how things workout to determine how you are going about your plan.
What are you waiting for ? Your friends boyfriend to tell u he likes you or you will ask him if he does? Why would him liking you be so easy to see ? I know it's very easy to see that you like him. You like him so much that you can't even wait for him to approach you (if that's even on his mind). To be so eager to have someone's attention is a bad thing, for that person to be your friends guy is horrible. You look really young so don't allow anyone (not some guy...or yourself) to turn you in to a jump down.
i would just wait until they break up. you don't want to hurt your friendship over something you aren't completely sure about. if they break it off, talk to your friend about it. if your friend is a true friend she'll listen and help you out. but it all comes down to who breaks up with whom.