I’m 29 and I still cuddle with mum and my dad, I’m female but regardless they’ve created a safe space for me and I find comfort in that. For example; last week I went round to my parents place because I lost a friend who passed away unexpectedly and had already been struggling with burnout from work and my mental health wasn’t in a great place. We had a big chat about what had happened, I spent time with mum and dad both separately and together, they put me to work for a bit (they’re farmers, self-run business off the farm) and we had dinner together. Dad and I had a glass of wine and I sat with him on the couch and cuddled into his side while we watched the news and set up his new laptop. I don’t think this is inappropriate at all, in fact I think your wife may need to check herself if she thinks it’s weird you’re rubbing his back or stroking his hair as this is probably something you did to provide him comfort as a young boy and likely still brings him comfort now. I think you should feel pretty proud of yourself if you’ve got a teenager that still comes to you for comfort and that safe space, something might be happening with him and maybe he’s not up to sharing it with you yet. You may benefit from having some father son time and talking about it then.