Multi-fiber, fiber optic cable assemblies and related fiber optic components, cables, and methods providing constrained optical fibers within an optical fiber sub-unit are disclosed. The optical fiber sub-unit(s) comprises optical fibers disposed adjacent a sub-unit strength member(s) within a sub-unit jacket. Movement of optical fibers within a sub-unit jacket can be constrained. In this manner, the optical fibers in an optical fiber sub-unit can be held together within the optical fiber sub-unit as a unit. As a non-limiting example, the optical fiber sub-unit(s) may be exposed and constrained in a furcation assembly as opposed to the optical fibers, thereby reducing complexity in fiber optic cable assembly preparations. Constraining the optical fibers may also allow optical skew, reduction of entanglement between the optical fibers and the cable strength members to reduce or avoid optical attenuation, and/or allow the optical fibers to act as anti-buckling components within the fiber optic cable.