Is he really not interested or is he just saying he isnt?

a couple weeks ago my best guy friend found out that i liked him and we talked about it and he said that he didnt understand why i wanted to be more than friends and said that he couldnt believe that i liked him and said that he didnt want to ruin our friendship....after that though he kept asking me questions like how long have you liked me for and why have you never said anything....at the same time however he is about to ask out this other girl who we are both friends with....is his reaction due to his impending relationship or is he really not interested?