Erin Reagan faced an unexpected reunion with her ex-husband Jack Boyle in the latest gripping episode of the popular cop drama.

Assistant DA Erin Reagan (played by Bridget Moynahan) has been separated from her ex-husband Jack Boyle (Peter Hermann) since the beginning of Blue Bloods, but fans are still holding out hope for a reconciliation in the near future. Could his return in last week’s episode on CBS be a hint they’ll get together again by the end of the latest season?

Blue Bloods fans have their fingers crossed for Erin and Jack to reconcile by the end of season 13.

Although they’re still not on the best terms, there could still be a chance they’ll put their differences aside to give their relationship another go.

Guest star Hermann’s return in the latest episode, Past History, has sparked further speculation there could be romance in the air.

In Friday’s instalment, Erin’s sister-in-law Eddie Janko (Vanessa Ray) overstepped her boundaries by intervening in a murder case and her professional life.

Viewers are hoping Eddie can eventually convince Erin to give her ex another chance, but for now, the two women are at each other’s throats again.

However, a large section of the fanbase is still adamant the show is setting up another Blue Bloods romance by bringing Jack back into the fold.

“One of my favourite episodes,” Twitter user @AnnMeye51812756 said after the show aired on Friday.

“I look forward to Fridays because of Blue Bloods. Hopefully, Erin and Jack will get back together. I love Joe Hill (Will Hochman), want to see more of him.”

@LoriAnnMartin19 tweeted during the hour: “This episode is getting so good.

“Maybe we will get Erin and Jack back together just in time for Valentine’s Day?”

@Sportsnthings1 predicted: “Something tells me Eddie will be the reason why Jack and Erin make progress towards being together.”

@Shaolinnative added: “Eddie’s not wrong…. who all roots for Jack and Erin to reconcile?”

While @deepostsstuff2 argued: “The thing that p****s me off the most is the Blue Bloods showrunners have clearly forgotten they wrote that Erin knew she was ‘addicted’ to Jack and that their ‘relationship’ is unhealthy for her.

“Jack and the writers should let her move on with someone new.”

Other viewers admitted they’re growing tired of the way Erin acts around her ex-husband whenever he’s brought in to help another case.

Having only appeared in a couple of episodes in most seasons, Jack’s heightened role in season 13 could be a sign he’s planning on sticking around.

Hermann has appeared in three episodes this season so far, and there’s every chance he’ll pop in with Erin again before the upcoming finale.

Meanwhile, other fans were keen for Eddie to start working with her husband Jamie Reagan (Will Estes) again as it’s been a while since they shared the screen for a substantial length of time.

There was more drama to be found with the Reagans elsewhere, too, as Joe received a dressing down from Frank (Tom Selleck) after breaking protocol with the FBI.

The series is now heading on hiatus for a few weeks but will be back with episode 14, Collision Force, in early March.