Throw away account because I know a few of my kids use reddit.

So I have three kids, an oldest daughter and two younger sons. When my daughter and older son were young we started going on camping trips pretty regularly. My wife hates camping so she was happy to let us go together as a bonding trip. My daughter loved it but my son HATED it and we could both tell. Well over the years my youngest was born and when he was a little older we'd take him too. Eventually, my middle son specifically asked me if it would be okay if he didn't go with us on the camping trip with us. I was disappointed, but understood, so he stayed home with his mom. Well over the years we went on at least one camping trip every summer, usually more, and after turning down so many invites over the years they eventually just stopped coming. By the time my daughter was in college it was just assumed that my oldest son did not want to go anymore, so we just wouldn't invite him. I wasn't purposefully trying to exclude him, we all just assumed we didn't want to go, even his mother, and so we'd plan the trip and go without him. 

Well, recently (my children are older now, my youngest is a senior in high school and my others have both graduated from college) we decided to go on another camping trip to celebrate my son graduating high school. As always, we just assumed my middle would want to stay home. 

One evening the whole family got together to celebrate my wife's birthday and it all came pouring out. My son very angrily revealed to us that he resented us because we never brought him on these family bonding trips. He told us he felt that we excluded him from everything, not only the camping trips, which I genuinely don't know what those other things would be. He said that just because he didn't want to go a few times when he was younger didn't mean that he appreciated never being invited now that he's older. He told us that he never asked to be invited because he felt like we didn't want him there. OF COURSE we wanted him there we just always assumed he was more than happy to stay home because he had never wanted to go in the past, so we never invited him. Am I the asshole for stopping the invites as time went on?