Let us get this straight: Joanna takes Ted to court for custody of Billy. They both fork over tons of money in legal fees and buckets full of tears and heartache. And then she decides not to take Billy after all? What the what?

If this was your reaction to the end of Kramer vs. Kramer, you're not alone. Here's the thing, though: Joanna isn't being wishy-washy; she's being selfless. She wants Billy to live with her, but she also wants to do what's best for Billy, and, as she explains, she's come to the difficult realization that what's best for Billy isn't living with her, at least not right now:

JOANNA: I woke up this morning. I kept thinking about Billy, and I was thinking about him waking up in his room with his little clouds over him that I painted, and I thought I should've painted clouds downtown because…

She trails off, sniffling.

JOANNA: And then he would think that he was waking up at home.

She sighs.

JOANNA: I came here to take my son home, and I realize he already is home. 

Much like when she left, Joanna's doing what she feels is best for her son, even if it's hard.

The ending is also careful to make it clear that this doesn't mean she and Ted are getting back together—although the original ending of the film was more ambiguous. It had Joanna and Ted both getting in the elevator to go back up to their son and what was once their apartment.

In post-production, that ending didn't sit well with director Robert Benton. At all. He thought it suggested that Ted and Joanna got back together in a magical Hollywood ending where Ted spontaneously forgot that Joanna walked out, then stalked him from a coffee shop, and then sued him. Benton wanted to make it crystal clear that this wasn't a reconciliation, it was an attempt at co-parenting, so he brought stars Dustin Hoffman and Meryl Streep back for a reshoot, and that's the ending we have now (source). Joanna and Ted are going to team up to raise Billy—and that's it.

Okay, maybe if things go really well they might join the same rec league softball team or something, too, but for now, they're co-parents, and absolutely nothing more.