The Maitlands not only live together; they die together, too. Guess they didn't mean it when they said that whole "'til death do us part" thing in their wedding vows.
Young and in Love
The opening moments of the movie establish Adam and Barbara's everyday life. These two kids are crazy in love: they laugh with each other and they can't stop kissing. Oh, and they adore their quaint, country house:
BARBARA: This is gonna be great.
ADAM: Are you sure you wouldn't rather go to Jamaica or someplace like that?
BARBARA: No way. There's no place like home.
Adam and Barbara have spent hours fixing up their house to be exactly the kind of restful and relaxing retreat they want. They even give each other thoughtful gifts for projects around the house. If they could, they'd live there forever.
Be careful what you wish for.
Roommates from Hell
When the Maitlands plunge off the covered bridge and die, their troubles begin. Being trapped in your dream home with your soulmate might seem like heaven—but then the Deetzes show up.
Charles and Delia Deetz are everything the Maitlands are not. Delia's an insufferable artist wannabe, and Charles is a New York real estate guy. They're pretentious and obnoxious, and worst of all, Delia can't stand the traditional look of the Maitland's beloved house. No way Adam and Barbara are gonna be able to spend the next 125 years with these guys. They say it themselves when they explain the situation to their afterlife caseworker, Juno:
ADAM: We want to get rid of the people who have moved in here. Barbara and I worked very hard on this house.
BARBARA: We probably wouldn't mind sharing the house with people who were...
JUNO: More like you used to be?
ADAM: But these people!
Juno suggests the Maitlands embark on a campaign to evict the Deetzes using scare tactics. Literally. It doesn't work so well. The problem is the Maitlands; they're just too nice, too sweet, and too charming. They want the Deetzes out, but they're hearts aren't in it. As the Deetzes' redecorating project goes from bad to worse, Adam and Barbara ramp it up a bit, but their ghostly hijinks only encourage the Deetzes to double down on their crazy plans for the house in Winter River.
That's probably why the Maitlands get so desperate and call Betelgeuse. They're not naturally terrifying, so they've got to outsource to someone who is. They also aren't being totally reckless here. Barbara only calls Betelgeuse once Delia and Charles have both totally failed to listen to reason. The Deetzes are living in a haunted house and they just don't care.
These ghosts are at the end of their ropes.
Okay, so the Maitlands hate the Deetzes, right? Well, not all of them. Adam and Barbara actually take a liking to Lydia. It helps that she can actually see them. It also helps that she's the only member of the Deetz family who isn't totally unreasonable.
At the beginning of the movie, we get hints that Adam and Barbara were trying to start their own family when their married life on earth was cut short. Could Lydia finally be the daughter they never had? Possible. They discuss their thoughts about Lydia when they debate scaring away the Deetzes for good:
BARBARA: Oh, Adam, I can't go through with it. I like that little girl.
ADAM: But, Barbara, honey, it's too late. We have to go through with this.
BARBARA: No, we don't. I mean, can't we rebel or something?
BARBARA: Adam, I want to be with Lydia.
Once Betelgeuse is finally out of the picture, Adam and Barbara take on the parental role that Charles and Delia never really seemed interested in.
It's a happy ending considering the unhappy circumstances, i.e., they're dead. Adam and Barbara get to love and care for a child—something they never got to do while they were alive. Lydia gets all kinds of attention from two people who have nothing better to do than hang around the house and help her with homework for next the 125 years or so.