Bob D'Amico / ABC / Getty Images North America 1 / 11
Bob D'Amico / ABC / Getty Images North America 1 / 11

Yikes!

Fans of ABC's "Castle" were devastated to learn on April 18 that star Stana Katic plans to leave the show after the eighth season, which comes to an end on May 16.

But the real shocker came in the aftermath of the departure news: Apparently the 37-year-old American-Canadian actress is leaving the series that made her a star because of her longstanding feud with on-screen love Natahan Fillion.

"Stana Katic and Nathan Fillion completely despise each other," a source told Us Weekly. "They will not speak when they are off set, and this has been going on for seasons now."

"This season, it got so out of hand they made Stana and Nathan go to couples counseling together," continued the snitch.

The tattler also alleged that Stana has cried on set over the tension with her co-star.

(Despite the insider's claims, a rep for the actress has told Us Weekly that Stana "had absolutely no issues" with Nathan. Meanwhile, his team has yet to respond to the magazine's request for comment.)

But The Hollywood Reporter echoes the reports that Stana, who negotiated a last-minute return for the series' eighth season, has been unhappy on the show and "has had repeated clashes with lead Fillion."

The duo have starred on the ABC procedural as mystery writer Richard Castle and NYPD homicide detective Katherine "Kate" Beckett since March 2009. Their characters tied the knot during the show's seventh season in late 2014.

Their off-screen drama reportedly led producers to split up the on-screen couple during the current eighth season, a decision that drew outrage from fans of the show who waited more than five years for the characters to finally tie the knot.

According to THR, insiders stress that it was ABC's decision to let Stana and Tamala Jones, who's starred on the series as medical examiner Dr. Lanie Parish since the first season, exit the series as the network looks "for avenues to reduce costs on the pricey drama and return it for a ninth season."

THR adds that ABC and "Castle" producers are in talks with Nathan to return for a potential ninth and final season of the procedural, which has yet to be renewed.

On April 18, ABC released a statement announcing Stana and Tamala's departures: "Kate Beckett has been a beloved character on our hit series 'Castle' for the past eight years. We are grateful for Stana Katic's talent and dedication to the series, and we hope to continue our relationship," it read. "Tamala Jones has also been an integral part of the series, and we are grateful she was a part of 'Castle.'"

No word yet on how Stana's alter ego will be written out of the series, but it looks like Castle and Beckett won't be getting that happy ending their fans so desperately wanted for them!