In this paper we develop a thermodynamicﾠperturbation theoryﾠfor two site associating fluids which exhibitﾠbondﾠcooperativity (system energy is non-pairwise additive). We include both steric hindrance andﾠringﾠformationﾠsuch that theﾠequation of stateﾠisﾠbondﾠangle dependent. Here, theﾠbondﾠangle is the angle separating the centers of the two association sites. As a test, newﾠMonte Carlo simulationsﾠare performed, and theﾠtheoryﾠis found to accurately predict the internal energy as well as the distribution of associated clusters as a function ofﾠbondﾠangle.