Compatibility isn't a percentage (and there isn't one in the couples book)
Every compatibility app hands you a number. 87%. 34%. And there's nothing you can do with that number except feel good or feel bad for a minute.
There's no percentage in the couples book. We didn't take it out and hide it: that calculation doesn't exist.
Why not
Because for a number to mean anything, somebody had to decide what each thing is worth. How much it counts that you laugh at the same things. How much it subtracts that one of you needs plans and the other can't stand them.
Astronomy doesn't make those decisions — whoever wrote the app does. A compatibility percentage is a stranger's opinion about what should matter to you, wrapped in two digits so it looks measured.
And even if the number were honest, it would still be useless: it doesn't tell you what to do on Tuesday when the same conversation goes wrong for the third time.
What gets read instead
When two charts cross, what shows up are the angles the bodies of one make with the bodies of the other: the same five as always, but now between something of yours and something of theirs.
There's no score in there. There are pairs. Your way of needing against their way of pushing. Their way of asking against your way of stopping. Each of those crossings is a concrete place where the relationship runs on its own or jams the same way every time.
The couples book is twelve chapters of that. It isn't two personal books stapled together: it's what happens between you, which is a different thing and can't be worked out by reading the two separately.
The part that costs
A book like this names what jams. By name, unsoftened.
That's what makes it useful and also what makes it a delicate gift. It isn't a test of how well you're doing: it's a description of how you work, including the parts you both already knew and never said out loud.
If what you wanted was a number confirming something, this book will disappoint you. If what you wanted was to understand why that argument keeps coming back, it won't.
You can read a chapter of the couples book free: not chapter one of a personal book, but a synergy chapter written from both charts.