Jessica Capshaw
Jessica CapshawReuters

Callie and Arizona have been friendly exes till now, but their relationship is going to get ugly in "Trigger Happy," the episode that will air April 21. Based on the synopsis for the episode, Arizona reacts when Callie takes an important decision about Sofia's future without consulting her.

And in the following episode titled "You're Gonna Need Someone on Your Side," their fight intensifies and the couple will put their friends in an uncomfortable situation.

There hasn't been much information on what prompts the former lovers to butt heads, but some fans have been wondering if the future plotline will see Arizona leaving Grey Sloan Memorial Hospital for a short while. It would make sense, considering Jessica Capshaw, the actress who plays Arizona, is currently expecting her fourth child with husband Christopher Gavigan. The actress announced her pregnancy in December 2015 through an Instagram post, but did not reveal how far along she was.

The show might not write in the pregnancy, but according to one fan theory, this season could very well see Arizona going away for some time. "She was pregnant before and they didn't write it in," one fan noted. "Remember when Arizona went to Africa and she and Callie broke up several years ago (while she was gone Callie hooked up with Mark and got pregnant with Sophia)? That was because Jessica was pregnant and they had to give her some time off."

Based on tweets from the cast of "Grey's Anatomy," Season 12 episode 22 might hold the clue to what's in store for Arizona. Actress Ellen Pompeo said in an earlier tweet that Capshaw will "rip your hearts out" in the said episode.

Here's Capshaw talking about episode 22.

 "Grey's Anatomy" airs Thursdays on ABC.