Why didn't he want to take a selfie with me?

I was at a formal party and this guy I have a crush on was there along with his family. Eventually, I started taking selfies with friends and his family and when i asked him for a picture of us he said and I quote, "oh I don't know.. I don't know if I should" with his head slightly down and avoiding eye contact.. eventually he agreed to it but it felt like a pity selfie so I deleted it. We have been acquainted for like 2 years and he was taking pics with others like 5 mins after I asked him for one.. Sidenote: i used to have a crush on his older brother but nothing really happened there and he is the one I truly ended up liking..
Why didn't he want to take a selfie with me?
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