When Michael first began seeing Kay, I really believe that his intentions were to stay out of the Family business,(except for using the connections to get a good job) ,and live a quiet, comfortable life with her. Once he decided to go down the path he did, despite his love for her,he relegated her to the status of "Mafia Wife". At Connie's wedding,while still a "civilian"he seems to enjoy telling Kay the Luca story in great detail. Contrast that with the classic "Don't ask me about my business,Kay". To sum it up,I think that Mike did love Kay,but the difference is that it was mutual and unconditional at first,but then after Mike became a "cheap Mafia hood", Kay was expected to be quiet,have babies,cook,and keep her mouth shut.