AITAH because I told my wife she isn’t allowed to ground my son?

My son is seventeen. My wife and I also have three more boys. Two are from before our marriage, but I’m legally their father now. They are all much younger than my son. My son is starting his senior year of highschool next year and hoping to get an athletic scholarship.

My son plans to spend all summer practicing. Yesterday my wife asked him to tidy up the living room and he said he was already on the way to the gym. She told him that he could go after tidying. He said he would do it when he got back and left without giving her time to reply. She sent him a text saying he is grounded and then called me to let me know.

I told her I would talk to him, but he wasn’t grounded. She said he disrespected her, and I said we could and would have a conversation about that, but there would be no grounding. This is my last summer with my oldest child and an important summer, because he’s trying to achieve something that can make or break his future. I’m not going to risk ruining either of those things unless it’s something really serious.

She was very upset. I texted my son that he wasn’t grounded, but that we wanted to talk to him when he came home. He said okay and texted me when he was leaving the gym to let us know he was on the way. When he got back we sat down and talked. He said he didn’t mind helping out, but that he was a busy person with a busy schedule and wasn’t at our beck and call. He said if he is asked in advance to do something he will, but he isn’t available to us at the drop of a hat.

My wife didn’t like that, but I said that was fine. I asked him if he would be willing to clean the living room, and he said he would after taking a shower. While he was in the shower my wife and I got into a big fight. She said I undermined her and all the kids will respect her less. I said she isn’t my oldest’s mother and final say goes to me with him. Any of our other kids and I wouldn’t do what I did, but she’s not his mom. She was very angry I said that and said she needed space from me.

We have only talked as much as necessary today, and I’m getting worried. We are supposed to be at a memorial day barbecue in an hour, and she just asked me if I could stay home while she took the boys without me (my oldest has plans with friends and already left). I am wondering if I’m the asshole here. My son always said that he would respect my wife, but she’s not his mother. He’s never cussed her, shouted at her or what have you. I think it’s fair that we stay consistent with her not being his mom. Maybe I’m being a bad husband.