There's a saying in the cycling world that goes something like "wherever your relationship is going it'll get there faster on a tandem"
I'd imagine a long trek like a Camino could well be similar.
But then again, maybe not.
Depending on your own life and how much the Camino is embraced there can be a whole lot of new things to deal with. You may be surprised. Perhaps your older, less prepared friend will turn out to be your rock, the one familiar thing in an ever flowing river. Someone travelling internationally for the first time they might be full of wonder, curiosity and be a great companion. Then again, they might complain all the time that it's not like Kansas, Toto. I know some well travelled people and I'd avoid travelling with them like the plague!
Similarly, depending on how much planning you have done a less prepared approach, at times, may be helpful, even enjoyable.
One of the truly great things about travel, but especially a well known camino route, is that it presents us with a chance to shed so much of our normal life and get back to basics. Real basics. Food, water and bed basics.
That can be incredibly liberating and can have a significant impact on our perspectives. And relationships.
However, you say you need to do this alone.
It's a bit late in the day!
But also, what is "alone"? You mention albergues. If there's other Pilgrims it'll be hard to be alone. There'll be others in the towns and villages you pass through. As well as locals!
Is it possible that this is just an expression of about-to-start-anxiety? You'd be less than human if you were as cool as the proverbial cucumber.
The advice to take a few days to get a feel is on the money, I'd think.
The advice for open, honest and direct communication is too.
The advice to travel separately and meet at the end of the day is followed by a lot of Pilgrims.
I often think that the heaviest baggage some Pilgrims carry isn't on their back at all but between their ears. That can be a real shame.
Expectations can be sky high. Fears too. Focusing too much on what the highlights are supposed to be can mean it is very easy to miss the highlights that matter - to us. Fears, on such a well serviced route in such an hospitable place are too often a waste of energy. Understandable, but still a waste.
If I learned one thing on my Camino it's that so many of the things that I thought were important turned out to be not that important, at all. There's a huge difference between thinking, planning, dreaming .......... and doing.
You're about to find out that difference.
Give the Camino a chance to show how it is going to treat you and your friend. Then respond.
Best of luck to you and your companion.