Nathan seems poised to be Meredith’s first significant post-Derek fling on Grey’s Anatomy. He may even turn out to be something more than a mere fling. But there is one thing that he can and will never, under any circumstances, be: another Derek. Take it from Ellen Pompeo, who plays Shepherd’s widow.

“There will only be one McDreamy ever,” she swears to TVLine. “You know, he’s not replaceable.”

Oh, we know. Viewers do, too. And luckily, so does Grey’s boss Shonda Rhimes. Well aware of the magic that Pompeo created with former leading man Patrick Dempsey, “the concept and the theme that she and I discussed [around the season finale] was, you really only get one great love in your life,” the actress says.

Which doesn’t mean that Mer can’t have fun with Nathan — or, if she so chooses, a whole series of Nathans. “Sure, you may have other relationships, and you may even marry again,” Pompeo notes, “but everybody has that one great love.” And for Meredith — not to mention legions of MerDer fans — that was Derek.

What do you think? Would you like to see Mer have another great love — and if so, who would it be?