It always bothered me that the beginning of ATAI, Clark was preparing and practising to tell Lois that he was Superman. He was interrupted by Jason Mazik's phone call. What bothers me is that Lois doesn't appear to remember that, and in many ways it is pivotal since Clark was going to tell Lois he was Superman...and it seemed that interrupted revelation happened not long after (perhaps the next morning) she had decided to say the scary words.
As far as this is concerned:
For example, Lois's change of mood at the beginning of WHALTTA. Once Clark is talking to her but as Superman, it seems like the tables simply turned. He becomes the ofended one and she starts almost apologizing, and so again the following morning at the Planet.
I've always interpreted it differently. When she is talking to Superman she was dealing with business first, so when the discussion turned more personal, it was easier for her. She told him that she needed time. She wasn't saying "No." she was saying "Not yet". So she knew that she needed some time to work through that he was Superman, and more importantly, that he hadn't told her. (Perhaps, when she got home that night and thought the whole thing through she'd remember the morning when he almost told her, "Lois, I'm super...". Even if she didn't, she would have time to think which makes her attitude the following morning make sense.
Clark, on the other hand, was being naive and human--a lunkhead. He proposed to Lois before she knew the truth and he hoped that she would marry him. He never thought about the ramifications if she found out, without him telling her, that he was Superman. Because at that moment he believed there was no difference between himself and Superman (I think if you asked him that at another point in time, he'd say there was a difference between Clark Kent and Superman). Anyway, he was hurt when Lois rejected his proposal. He heard "No", not "Not yet". And because he's human, he was petulant.
I think they both were in character there. (And the writers had to draw out the developing relationship.)
That's my take on these scenes.
gerry