Advancements in robot technology are allowing for increasing integration of humans and robots in shared space manufacturing processes. While individual task performance of the robotic assistance and human operator can be separately optimized, the interaction between humans and robots can lead to emergent effects on collaborative performance. Thus, the performance benefits of increased automation in robotic assistance and its impact by human factors need to be considered. As such, this letter examines the interplay of operator sex, their cognitive fatigue states, and varying levels of automation on collaborative task performance, operator situation awareness and perceived workload, and physiological responses (heart rate variability; HRV). Sixteen participants, balanced by sex, performed metal polishing tasks directly with a UR10 collaborative robot under different fatigued states and with varying levels of robotic assistance. Perceived fatigue, situation awareness, and workload were measured periodically, in addition to continuous physiological monitoring and three task performance metrics: task efficiency, accuracy, and precision, were obtained. Higher robotic assistance demonstrated direct task performance benefits. However, unlike females, males did not perceive the performance benefits as better with higher automation. A relationship between situation awareness and automation was observed in both the HRV signals and subjective measures, where increased robot assistance reduced the attentional supply and task engagement of participants. The consideration of the interplay between human factors, such as operator sex and their cognitive states, and robot factors on collaborative performance can lead to improved human-robot collaborative system designs.