I prefer doing certain things on my own. Shopping is one of them. If I have someone with me I feel pressurised to hurry up and if they're taking longer than me I feel bored.
When I'm hiking I often walk ahead or behind as well. Sometimes I like to have the peace to take it all in without a lot of chatter.
When I'm in a conversation with someone I tend to give them my full attention which means I can miss what is going on around me.
You said it right! I see we have a lot in common. Although I hate shopping, I feel the same when someone is with me.