Curve clipping problem

Hello, everyone,
Thank you for your help, I have almost completed the preliminary model construction.
But in the end I still have a problem, as the image illustrates.
Finally, I encountered a situation regarding the problem of cropping after line projection.
Like picture 2, if the surface is surrounded by two surfaces, what should be done to crop after projection? My current method is to manually select the curve, which is a waste of time.In this case,
is there any better The way?

Curve clipping (405.6 KB)