The line is a single entity folding over on itself with no segments. There is no "separation.

I am not sure how to arrange to Unfold that particular shape. For me it is starting to get into the non developable arena and want to go to software meant to do that.

Maybe Michael can direct unrolling that cylinder?

Here is a video where I use Pepakura to unfold it. But you are now "dicing up your model". So you will have to make a determination on tolerances and accuracy