For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Lucy wants to be in love, and God (aka Bob) is happy to oblige. Even though he is a lazy good-for-nothing, Bob knows how to seduce a lady. (Not to mention, turn into a giant, rapist animal if she doesn't give in.) There are two more major decisions in the first act: (1) Mr. B decides to resign and to save his whales; (2) Estelle decides to save the taste and last-of-his-kind Eck after he gets gambled away to her hungry dad.
Act II
All the balls are in the air. Bob and Lucy are dating, but they still haven't had sex. She's starting to worry that he's a little crazy. Earth is being totally flooded, because the weather is tied to Bob's moods. Estelle managed to get Eck six weeks to live, but he's still going to get eaten. And Mr. B's whales are still totally done for.
Act III
Welcome to the final act. Bob has sex with Lucy, so the flooding is over but he totally ignores her afterwards. The moms get involved, and neither one wants her kid dating the other one (rightly, we might add). Bob does a crazy fix for the whales, making them fly; and, of course, Lucy ends up finding love with Luke, the guy who was mean to her. (Girls, right? They never want the nice guy.) Oh, and Bob gets transferred to a new assignment, leaving Mr. B and Estelle to watch out for Earth.
Well, that pretty much ended exactly the way we'd want it to.