Understanding the fracture behavior of single crystals is critical for understanding failure mechanisms in polycrystalline metals. This study investigates the crystallographic orientation-dependent fracture behaviors of various Nickel (Ni) single crystals subjected to uniaxial tension at quasi-static rates and room temperature. We identify two distinct failure modes in single crystals: some single crystals exhibit fracture through necking, while others fail along a slanted failure surface. To elucidate the mechanisms behind these divergent failure behaviors, we conducted a comprehensive analysis using crystal plasticity finite element (CP-FE) and crystal plasticity coupled phase field damage (CP-PFD) simulations. Our crystal plasticity analyses indicate that the direction of the active slip systems, particularly in the lateral (transverse and thickness) directions, plays a critical role in influencing the failure behavior of the crystals. We demonstrate that a simple calculation of the stress projection factor, based on the initial crystal orientations, can yield efficient and accurate predictions of the failure modes in single crystals in sheet form. In contrast, other local fields, such as stress and strain-based indicators, showed minimal correlation with the observed failure behaviors. In addition, the CP-PFD model effectively predicted ductility and failure behavior in these single crystals. This study elucidates the intriguing fracture behavior observed in single crystal materials and provides a predictive framework for evaluating failure modes.