Yes, those scenes in bed with Kay were the only ones where Michael actually looked happy and even playful.
But, as that flashback scene at the end of II shows, the guy was inclined toward melancholy. He was also an extreme controller--even then, if you take what he told Tom at face value ( You ...talked to my father...about my future..."). People who have such lifelong behaviors are often described as having "obsessive/compulsive disorder."