"Castle" just premiered its eighth season and one of the most highlighted news surrounding the series is the breakup between two core characters, Rick Castle (Nathan Fillion) and Kate Beckett (Stana Katic), as the former asked to have some space from their union.

The premiere was a shocking twist that left "Castle" fans devastated, especially those who have always rooted for the couple.

As previously reported, showrunners Alexi Hawley and Terence Paul Winter already revealed that fans should not worry because Rick and Kate won't be apart forever.

The breakup was a just a way to spice things up in their relationship and give fans something to root for.

However, it seems that the storyline did not only surprise fans but also Fillion himself. A report from TV Line stated that Fillion was even shocked when he learned that the showrunners would break apart the relationship between his character and Katic's.

"First of all, I asked them if they were high," the star told TV Line.

"Second, they reassured me that what was going was they wanted to get back to a time when people were rooting for the couple," he continued.

Surprised by the breakup he may be, Fillion ultimately admitted that Hawley and Winter did an amazing job with the story.

Now, the show is back to the time when Rick and Kate were working together with some tension, with him also working on how to win his wife back.

In fact, it was reported by Latin Post that the two will continue solving cases and working aggressively, and such is one way that Rick thinks would bring them together once again.

He'll be more focused on finding the ways, rather than digging deeper into the truth as to why she had decided for them to split.

On Monday's episode, Kate and Rick were seen working together on a case that involved Rick's childhood idol.

Rick, other than determined to solve the case, was also seen pursuing Kate; still, they are not getting closer to a reunion just yet.

A new episode of "Castle" airs every Monday at 10 p.m. EST on ABC.