It is my belief that girls can be equally confusing.
From his behavior it would suggest that he is attracted to you, but for some reason he does not want to create a personal relationship with you. This may be because he is too shy or because he is unwilling to enter a relationship for personal reasons. These reasons may include a concern that he is unable to provide you with what you would require in a relationship or possibly that he does not feel he is ready for a relationship with you, but is enjoying playing around with the idea. Commonly guys do not tease girls unless they are attracted, but there can be many reasons why they do not take it to the next level (including possible current relationships). You could take the initiative to ask him out, or alternatively try to separate him from his group and talk with him, perhaps over a coffee or for some other excuse, to ascertain, in a subtle manner, his reasons for abstaining, or perhaps to gauge his level of interest for you.