Romances will be turned on their heads as “Grey’s Anatomy” couples define their relationships and, in some cases, take a deeper look inward during Season 13, episode 4.

According to a synopsis for the show, titled “Falling Slowly,” Meredith (Ellen Pompeo) and Riggs (Nathan Henderson) may be looking to put a label on their fling. Doing so, however, could have grave consequences for the already rocky friendship between Meredith and her half-sister Maggie (Kelly McCreary), especially after the many opportunities she’s given Meredith to tell her about her romantic interest. Additionally, Amelia (Caterina Scorsone) will question the status of her marriage with Owen (Kevin McKidd) — which is still in its early stages. It is not clear what the catalyst for her confusion may be.

While relationship drama unfolds, others at Grey-Sloan Memorial Hospital are just trying to find stable ground. Jackson (Jesse Williams) and April (Sarah Drew) dive head first into parenthood — trying to make it work in spite of the fact that they’re divorced — while Alex (Justin Chambers) tries to turn over a new leaf after violently attacking DeLuca (Giacomo Gianniotti)  in the Season 12 finale. The synopsis for episode 4 suggests that although he’ll attempt to put his best foot forward, his efforts will be futile.

During Season 13, episode 3, it seemed as though Meredith and Kelly had reached a turning point in their relationship. After demanding that a family settle their differences in the emergency room, Amelia decides to try her luck with the half-sisters. She confronts the pair, revealing to Meredith that Maggie feels as though she isn’t listening to her. Amelia orders that Meredith and Maggie talk to one another about anything and everything, threatening to move back in. They oblige and decide to go out to dinner together. Rather than focus on herself any more than she has been, Maggie urges Meredith to share some details about her personal life. She questions whether her sister is romantically interested in anyone — the perfect opportunity to come clean about her romance with Riggs. Meredith claims she’s not seeing anyone or looking to get involved, which may come back to bite her in episodes to come.

“Grey’s Anatomy” airs Thursdays at 8 p.m. EDT on ABC.

“Grey’s Anatomy” Meredith (Ellen Pompeo) and Riggs (Nathan Henderson) will consider defining their relationship during Season 13, episode 4 of “Grey’s Anatomy.” Photo: ABC