Our jaws hit the floor when Arizona (Jessica Capshaw) cheated on Callie (Sara Ramirez) with Dr. Lauren (Hilarie Burton) on Grey's Anatomy Season 9, Episode 23: "Readiness Is All." We may have screamed at our TVs. And after thinking about it all night, we've decided: We don't like this plotline. At all. And no, it's not just because we love Callie and Arizona together. 

Relationship drama is part of the Grey's Anatomy package. If it's not half of a couple taking a job in Africa, it's a surprise baby or a terrible car crash. As Shonda Rhimes has often said, we can expect a happy ending ... when the show is over. Until then, there's always going to be conflict. That's what makes the show an addictive delight even after nine seasons.

Here's the catch: When Grey's is going strong, the relationship drama makes sense. Sure, the show is soapy and full of bed hopping, and the cast runs into more life-threatening disasters than is even halfway reasonable. But under all of that, the emotions are honest, and when characters make mistakes, we normally understand why.

Take April and Jackson's breakup earlier this season. We've make no secret of being Japril shippers here at Wetpaint Entertainment, but as much as we hated their split, it made perfect sense with their characters. We bought Jackson deciding to go all in when he thought April was pregnant. When it turned out she wasn't, we also understood why April unthinkingly blurted out her relief and why Jackson was so hurt he ended things. The pregnancy scare may have been contrived, but the reactions weren't.

The last time Grey's had a big cheating storyline with a major couple Owen (Kevin McKidd) and Cristina (Sandra Oh) in Season 8 it was devastating, but it felt right. Owen and Cristina's relationship was coming apart at the seams because of their fundamentally different desires about family and Owen's residual anger about Cristina's abortion. It wasn't right of Owen to cheat, it broke our hearts, but it fit with where Owen and Cristina were at the time. It was one peice in a carefully constructed season-long puzzle.

That brings us to Callie and Arizona. Our problem isn't that Arizona's cheating is sad, or that it might break up a fantastic couple. It's that we don't get it. If either Callie or Arizona had cheated earlier in the season, we would have understood. Arizona was struggling with her leg, Callie felt lonely and unloved. There was a lot of hurt, and one of the woman giving in during the heat of the moment would have worked for their story at the time. It would have sucked, but it would have worked.

However, over the last third of the season or so Callie and Arizona finally managed to repair their relationship. They were doing well. They were happy, they were supportive. Why would Arizona cheat just as things were going well?

Jessica Capshaw has tried to explain it as part of Arizona's reaction to everything she's been through. While we can theoretically see how that might work, we think the writers missed the mark on this one. To us, this plotline came out of nowhere and didn't mesh with what we understood of Arizona's headspace. Maybe there's another version of this plot that we buy, but this felt like being blindsided by drama for the sake of drama.

Do you agree, or did Arizona's cheating make sense to you? Share your theories in the comments below.

Catch the Grey’s Anatomy Season 9 finale on Thursday, May 16, 2013, at 9 p.m. ET/PT on ABC.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.