Guy's Behavior

Guy in friends group being very rude to me for apparently no reason?

More than one year ago, after lockdown, I started hanging out with a girl I know and her friends group in the new city I moved to and much to my initial embarrassment, I realized one of her best friends was a guy I had recently chatted with but never met on a dating app. I joked about it with him, I told him something like “well if we have friends in common tinder dates are excluded” and that was it. I met him again a few times and he seemed to be nice to me so I started being friendly and behaving to him just like to any other guy/girl in the group. With time however; the more I felt at ease with him and approached him to chat or wrote to him (again - just as with other people in the friends group) he became very cold and even stopped replying to my messages - in which I always expressed friendship not interest. When I see him, he avoids me. When he organizes things, he invites the whole group except me. There have never been discussions, we always just met through the group and after a few initial jokes the tinder thing wasn’t really mentioned again… and our interactions were always very civil, like those of people who don’t know each other well - no discussions or expressions of different opinions etc. i am clearly missing something but I don’t see what?

Guy in friends group being very rude to me for apparently no reason?
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