Meh, it doesn't have to be friction. If the goal is to ensure your other team member sees the changes you're making before they're merged in a pull request both accomplishes that and gives you both a place to put some notes related to that process.

I think you're ascribing too much ceremony to this. It's useful to have something written down for any discussion about these changes, and a pull request is as good of a place as any for that. Plus it ensures everything is all set up to merge once you're both satisfied with the changes.