Somebody, write Grey’s Anatomy‘s Maggie a prescription for a pint of Häagen-Dazs and a Netflix tearjerker, stat. When she learns that her half sister slept with her new crush, “I think she’s going to be crushed,” Kelly McCreary tells TVLine. “Genuinely crushed.”

Not only had Maggie really begun to like Nathan, she loved the idea of being in love. “She expresses that a lot in the finale,” previews the actress, “so [when she finds out] ultimately that it may not be a chance for her to be in love, I think she’s going to be heartbroken.”

To add insult to injury, it wasn’t just anyone that McKiwi bedded — well, back-seated, technically — it was Meredith, the sibling with whom Maggie worked so damn hard to bond. “So [that closeness] has to be destroyed,” says McCreary with a laugh. “If you’re in a good place, that’s not sustainable.

“I think that the next phase of Maggie and Meredith’s relationship,” she adds, “is going to [involve them] having to draw some boundaries around their relationship.”

And maybe battle lines as well. After all, Maggie could choose to fight for Nathan. “I guess the question is, does she value her relationship with Meredith more than she values her desire to find love,” McCreary muses, “and does she believe that Riggs is the right match for her?”

At least for the moment, Maggie’s ignorance is bliss. In Thursday’s Season 12 finale (8/7c, ABC), Amelia’s maid of honor “is dealing with trying to get her and Owen’s wedding going,” McCreary reveals. “So she’s dealing with managing Amelia and Meredith as usual.

“It’s a really great culmination of how we’ve seen Maggie invest so much in this sisterhood,” she continues. “She’s just always trying to keep everybody happy!” (Reporting by Vlada Gelman)

What would make you happy? Would you prefer to see Nathan with Maggie or Meredith? Or are you hoping Maggie and Andrew will reunite? Hit the comments.