I have been playing through Journey multiple times now. On my third or fourth go round I went in with the mindset of trying to catch every glyph, mural and trophy. Luckily for me I met a companion dressed in white almost immediately and they guided me to everything I was missing. This was just what I needed, they were great, it was awesome.

The next day played again and I used my new found knowledge to lead another new red companion round the game. It was only at the end up that I realised by the pattern on my new friend's robe meant that this was there first playthrough of the game and I had showed them everything. I've robbed that guy of the chance to go exploring by themselves.

So, is this a thing? Were they grateful to me or irritated? What should you do in that situation?

I sent them a message on PSN, they didn't reply.

Also, I'm new around here, hi!

Welcome to the forums :)

I think what you did was fine, really. They didn't have to follow you to everything you showed them if they wanted to experience it on their own. I actually played the game offline my first playthrough specifically for that reason, so had that been their desire, they could have easily done the same or just ignored you or any other people they came across online,

I second what @PixelPrinny said. I don't think there's really any sort of etiquette in Journey, because I can't think of any way where you can actually be a jerk. If someone decided to follow you around, that's their call, not yours. And who knows, they may be helping someone else out now, too.

Also, welcome. :)

I showed the game off to my sisters fianceé and he seemed to enoy it, though right at the very end the flying stone snakes apparently stressed him out so much that he had to stop playing (he doesn't really play games otherwise). Problem was the companion he had along right at that moment was a chatty fellow who, by the looks of things, were playing the game for the first time.

Thinking about my own first experience with the game I couldn't just abandon the guy at the finish line. It felt like that would ruin his companion experience, so after a while of trying, and failing, to coax the fianceé into finishing the game, I decided to pick up and accompany the other player to the end myself. Considering it stuck around and called for "me" when my character had stopped and sat down for quite a while, I can imagine that he was quite attached to his companion.