The load applied to the pulley varies sinusoidally, not proportionally, to the angle between the pulley anchor line and whatever ropes are attached to it.

If the angle through the pulley is 180 degrees or straight, the cosine of (180/2) degrees is zero, and no load is applied to the pulley. If the angle through the pulley is zero, meaning the rope doubles back on itself, the cosine of (0/2) degrees is one, meaning each end applies all of its force to the pulley, and the load is double. At 90 degrees, the cosine of (90/2) is 0.707, so each rope applies 0.707 times its force, or 1.414 times total. Thus the load on the anchor line is 1.424 times what it is on one line.

If you add friction to the pulley, then you have to start adding the components separately, and the above simplified math does not apply. A pulley with friction will simply allow the ropes to change angles, and potentially loads depending upon how they are fixed, until it reaches equilibrium. Thus each end of the rope through the pulley may not make the same angle, and then must be calculated independently. In order to calculate the load at the anchor line, the loads on each rope and their angles must be used to calculate their contributions to the load on the anchor line independently, with an equation like L3 = L2*sin(A23) + L4sin(A43) where L2 and L4 are the loads at 2 and 4 respectively, and A23 and A24 are the angles the ropes from 2 and 4 make with the anchor rope at 3.