Everybody knows that marriages require work to succeed.

Strangely, though, no one ever told me that having a positive, lasting relationship with my parents takes work, too.

Half of marriages end in divorce. But what percentage of children have always liked both their parents and enjoyed spending time with them? It’s darn well less than half.

If you aren’t careful, you will find a way to dislike your child. If you aren’t vigilant, you could simply run out of things in common and stop talking to each other. It doesn’t make you bad people, it just makes you human.

Writer/director Greta Gerwig made a perfect little indie film about a lousy mother/daughter relationship.

Saoirse Ronan (“Brooklyn”) stars as Lady Bird: a high school senior in Sacramento, California.

Lady Bird is a normal, relatable teenager. She’s not so great at school, not so smart with boys, and has a terrible relationship with her mother.

Laurie Metcalf (“Rosanne”) plays Lady Bird’s mother Marion. Marion probably never should have had kids and she quietly knows it. When her husband is laid off, Marion goes from hard-working mom to put-upon, unhappy grump.

Marion will never understand why Lady Bird isn’t grateful for all that she has done to sacrifice for the family. And Lady Bird will never understand why it is horribly stressful for her mother every time she mentions that she wants to go to an expensive east coast college.

“Lady Bird” is as empathetic and relatable a film as you’ll ever see. Writer/director Greta Gerwig is an explosive talent. It’s a shame (and a little sexist) that critics are assuming that the movie is autobiographical.

None of the other Best Director nominees are being accused of this. No one is assuming that Christopher Nolan was a British soldier because he couldn’t have made “Dunkirk” so believable if he hadn’t been. No one is asking Guillermo Del Toro how many magical sea monsters he slept with to research “The Shape of Water.”

My point is: “Lady Bird” is a first-rate film and Greta Gerwig deserves more credit than she is getting.

The best scene occurs 2/3 of the way through. Lady Bird is trying on prom dresses with Marion and there is tension as always. Suddenly, Lady Bird bluntly asks her mom: “Why don’t you like me?”

Marion, taken aback, can’t even bring herself to lie. She doesn’t like her daughter. She’s a mom who is doing the best she can for her family. That’s the best she’s got.

Greta Gerwig’s conclusion is perfect and real. Maybe, just maybe, Lady Bird and Marion will learn to like each other someday. But it’s certainly going to take some work.