Rhimes told TV Line that the death of Henry (Scott Foley) will bring up the couple's issues.
"[It] is a catalyst for Cristina [Sandra Oh] and Owen [Kevin McKidd] to face what is the real problem in their relationship, which is Cristina had this abortion that Owen's not comfortable with," she said.
"The unresolved tension about the abortion really explodes in these upcoming episodes. Everything just blows up to holy hell."
However, Rhimes hinted that happier times could be ahead for Meredith (Ellen Pompeo) and Derek (Patrick Dempsey), who were reunited with their adopted daughter Zola in last night's episode.
"You're seeing tremendous growth in them as a couple," she teased. "And we're watching Meredith figure out what she wants to do now that she's stepping back from neurosurgery for the good of their relationship.
"We're going to see what that means for her. And we're going to watch Derek really fight to be the [best] doctor that he can and put his all into what's going on with him and Meredith."
Grey's Anatomy airs on Thursdays at 9/8c on ABC.
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