As you can see, the "meet-the-parents" plot tends to bring out and accentuate the differences in race, gender, well-being, culture, religion and age — depending on the author's intentions and optics used. Themes of the films mentioned above are rather social, not existential, though we can interpret them in many ways. On the one hand, we can find a moralizing message like «try to know your partner better before marrying him/her». On the other hand, there's a warning, - «Take a closer look at your relatives! They might be frenetic!» If you try to look at it from a culturological point of view, you'll see a sign of decay of the family institute. It is not a safe space anymore, and traditional values are unable to change it in our minds.
But it's not just about society: it's about our fear of not being accepted by our loved one's family. Other parents are scary, but still we do our best to gain their trust. «It's good when people you like like each other», — says the character of I'm Thinking of Ending Things. And he's goddamn right.