Meredith, played by Ellen Pompeo, and Derek's, played by Patrick Dempsey, storyline is looking to close with the shocking ending of episode 16 of "Grey's Anatomy."

Meredith was debating throughout episode 15 whether or not she wanted to keep Derek around in her life. She later decided that she wanted him to be with her during the good and bad times. To give herself some verification of her decision she calls Derek, who is working in Washington D.C. for now.

Instead of Derek answering the phone a mysterious woman answers, leaving Meredith to question if Derek is actually cheating on her or not.

In a promo for episode 16, "Don't Dream It's Over," Meredith delves further into the situation. In the clip, Meredith goes into the break room where Alex, played by Justin Chambers, and Maggie, played by Kelly McCreary, are resting from their shifts. She tells them that a woman answered Derek's phone.

Maggie was more interested than Alex as she and Meredith discussed the woman's voice. "She was perky. And she sounded happy and tail with a lot of great hair," Meredith said. Alex was dumbfounded at the two, asking how on earth they could describe a person's physical appearance just by their voice. The two women ignored him.

When asked if Meredith had talked to Derek since the mysterious woman answered, she said that she keeps letting her phone going to voicemail. The clip ends with Meredith asking, "He's not cheating on me, right?"

Episode 16 aired on Thursday, March 19 on ABC. The episode is now available to watch on the ABC website.