My first night in St. Jean, I went out to dinner with other guys. In my head I thought, "So, these will be the people I walk to Santiago with." I was separated from them the first day and never saw them again.
I met a group of people in Valcarlos and thought, "Oh, so THESE are the people I'll walk to Santiago with." There were six of us in that group. Two days later, only two of us remained, but we picked up 2 others. We added another one to our group on Alto de Pardon. "Okay, so now we have it, our Camino family." But just 2 more days later, it was only myself and the person we picked up at de Pardon. And I was with her for a few more days until we parted at Santo Domingo. I spent the next two and a half weeks pretty much on my own, and figured I'd be walking into Santiago by myself. Sure, I would see more or less the same people at the albergues at night, but I was no longer walking "with" anyone.
By this time I was thinking, "Okay, looks like I'm going at this alone." But upon reaching Portomarin and for the rest of the week, I met more people and was once again lucky enough to be adopted into a Camino family. And I did not walk into Santiago alone like I had thought I would.
I guess what I'm trying to say is that as much as you can try to plan to walk with someone, sometimes things come up. They have a different schedule than you. They can take more time or they need to hurry. Maybe they just walk at a different pace or maybe they are just walking a section of the Camino. People will come into your pilgrimage and sometimes they leave. Be prepared for that and be grateful for the time you have with them!