M effect 2: Can shepard(male) romance with every female character or just one?

Some say that i cant get jack's loyalty unless i bang her. Also is it possible to have perfect relationship with every person on our team like Miranda, Samara and our istant Kelly at the same time. . . ? Im playing my game with only paragon so please suggest what to do to get loyalty of all. I played first but jack died since there was a fight between miranda and jack and favored miranda. How do i get both of them to be loyal. . . ?