Apologies for writing as a "man of reddit" if the advice is unwelcomed. However, here is a view from the other side - even if just one thing helps to provide insight or change your view of things.

I think you need to take into account the person. There are guys who very comfortable asking anyone they are interested in out, and then there are the other guys. These guys can just be shy, simply don't have high self-esteem as to believe they are being hit on, or even just don't want to find out they accidentally mistook kindness for being hit on (reddit ladies have been quite clear how many times kindness has been misinterpreted lol). I've found out that I was simply oblivious a couple times that I'm aware of, and one of those times was even someone I was interested in.

I know asking someone out can be pretty frightening, especially if you are friends with this person. Then it comes down to the fateful question of risking the friendship for a shot at a relationship. If early enough in the friendship, it can obviously be rebounded from but we all fear the older friendships where it can sort of shift the dynamic if it is unrequited.

I'd say if you are serious about it, you could drop one more less-subtle advance and see if he gets the hint. If not, consider asking him out. There are guys out there who won't ask even if interested, as much from fear of misreading signs as of rejection. If he won't take the hint, then on behalf of the many non-Don Juan's (Non-Juan's?) of the world, please ask him out :-).

Obviously I don't know all the specifics, but don't always assume your advances are unrequited - the object of your affection may just be oblivious or shy and appreciates a woman who takes the initiative.