The lines are not straight from the handle to the leadout guides. They trail in what should be called an accelerated catenary form. A catenary curve represents the sag of a cable between two supports - at uniform cable weight. In addition to the simple weight of our "cables", they are also subject to increasing drag due to their speed through the air.
At the handle, this speed is approximately zero. At the leadout guides, the lines are going as fast as the wing is, at that point. Drag increases as the square of the 'local' velocity.
The curve becomes 'deeper' approaching the leadout guides. Our lines, whether cable or solids, take that curve. As slack 'cables' they can only carry the pull load within their own diameters. They can't push or pull in any other direction!
The crucial thing is to 'aim' the cable pull AT the (fore and aft) CG. Programs, or apps, can calculate this trail angle by length to the guides, velocity, line diameter and number of lines. (the LINE programs.)
IF the pull, aimed by the trail angle at the leadout guides, aims ahead of the CG, it will tend to pull the nose in toward the center of the flight circle. ...And vice versa.
In normal flight, the centrifugal load (I know, it is a centripetal load, but...) is divided equally between the two lines. Their midpoint defines the effect of net line pull. In maneuvers, the 'active' line takes more of the total load (the aim of net pull shifts toward that line and its leadout guide. These are temporary changes, and greatly overcome by inertia and aerodynamic factors, usually, until we resume 'straight' flight with the pull about equal on each line.
NOT trying to show off or anything! These things have been kicked around many times. What I'm trying to do is put them together in a simpler way than many discussions of individual parts have not done. Have I had any success at that?