He seems very...

I am completely turned off by Nathan Fillion after his twitter response. Out of respect for Stana and fans of the series, he should have ended the show alongside her exit instead of dragging out a show that very few people will want to continue watching without their dynamic. I don't care what drama was happening behind the scenes. Have some integrity man.

Quite naive statement. He's an actor for hire, who earns thanks to his play. You don't know the real situation, you don't know the context of the case and express your opinion very easily.
Do you expose your work and your future in the name of solidarity with a colleague from work?
It's known that Nathan is in the middle of the negotiating his contract for the new season. No one is altruistic in terms of millions of dollars

What do you expect to Nathan flake out (I hope that is the proper expression in English) on ABC? What opinion he will have? Who will employ him in the future? Stana Katic fans club?

PS
I have the same opinion about the present show (and it's future) as you. Besides, it's money and decisions ABC and Nathan's private business, I have the right not to watch.

/from new girl with limited language skills /

I'm not naive to the ways of money and how it drives people, but I don't think it's unreasonable for an actor who's currently in negotiations to renew or not renew a contract to end the show while it still is what the fans fell in love with. Instead, if it gets renewed for another season it will overstay its welcome (even more than it already is) and will have a poor ending. Because what are there options here?

1) Kill Beckett, unhappy ending for her character
2) Beckett just up and leaves, arguably also an unhappy and out of character decision

I'm aware that television shows employ a ton of people and that Nathan Fillion being the title character holds the fate of everyone's jobs, but television shows also come to an end. 8 seasons is an outstanding run and has already long surpassed the 100 episode syndication requirement. The ratings have been declining anyway and breaking up the main duo is not doing them any favors. Instead of trying to squeeze every last dollar out of this show and completely destroying what made it good in the first place in the process, stand with your 8 year long partner that built the show with you. The show wouldn't been successful without Stana Katic and the chemistry they brought to the screen. So how about instead of being disrespectful the fans, Stana, and the quality of the show and having it end after season 9 when it inevitably gets cancelled sans Beckett, Nathan as the star of the show makes the decision to move on to something else while there is still time to end the show in a satisfying way.

I think it's the right thing to do. The show is near the end of it's life anyway, so they should end it now while it can be salvaged instead of next season when they're picking up the pieces of the show it used to be.

Just my thoughts.

I agree with your opinions on the fate of the series and ABC's decisions. I was addicted to this series (first time in my life). I started to watch this on the internet last year. And since last September I began to complain of what began to happen in this season. IMO, all this mess is due to new showrunners, who couldn't cope with the task. Craps main arcs (LokSat/separation), miserable dialogues, stupip and shallow jokes, unreal low crime stories and the most important: making pathetic caricatures of the main characters

Just like you (in the current situation), I'd like to end the show with dignity in this season. Although as you can see it doesn't happen - because of the decisions ABC. I believe that this's the wrong decision, but it's their money and decision.
Just like you, I think the series has no chance and ABC (due to greed or lack of knowledge) will destroy the opinion of the show, will destroy a great show.
but I don't think it's unreasonable for an actor who's currently in negotiations to renew or not renew a contract to end the show while it still is what the fans fell in love with. Instead, if it gets renewed for another season it will overstay its welcome (even more than it already is) and will have a poor ending
I don't understand this sentence (I am Polish and I live in Poland) - lost in translation. What Nathan has to do with the end of the show? I don't understand the context of this paragraph.

I try to understand the decision of Nathan. For nearly two seasons his character was slowly marginalized becoming own shadow. With brilliant, intelligent, endowed with extensive, vast knowledge of the writer became a caricatured character, the background for his wife, an idiot and moron, a person who believes in genies and checks if the carpets are flying. Nathan as a professional playing this character without complaints and discussions. I don't think that he was happy to see in which direction the development of his character is heading.

Nathan as a professional knows that he has very little impact on the decisions of a powerful company, and if the company has decided to extend the life of the show (even in such a terrible way destroying the show) just wants to work and earn additional money. If ABC doesn't care about the show and fans, why Nathan has to feel responsible?

/from new girl with limited language skills /

I think you are completely wrong. He seems like one of the most good natured & awesome guy ever & it was that stana chick who's the arrogant one. His twitter response was very professional especially considering the animosity between both of them. I hated her character on "Castle" from day one & was elated to hear she wouldn't be on next season - finally a season without that bitch! But then ABC cancelled it entirely, which sucked. I haven't seen the finale yet but I'm hoping they killed off her character.

I am not sure I ever warmed up to her either. I think relationships kill the unique persona in every character on television anyway. I think the only time I ever disagreed was with Killian/Hook and Emma on Once Upon A Time... and that is because Colin O'Donoghue makes an AWESOME love interest... *smolder.

But (usually) I like to see their strengths and weaknesses conveyed without 'a girlfriend' or boyfriend always nipping at the storyline's heels.

And WTF? These people must not know anything about Nathan. He's not a chump, but he's not a bad guy at ALL. He's funny, generous, hard working, ethical..

This guy is humored by pups and kittens, ooh, what a bad bad guy. Give me a break.

Maybe he thinks he has something to offer the show regardless of Kate too. Why not? They don't have to divorce. They speak off screen, I'm sure she wasn't crying about it... oh Nathan, how could you do this to me... *whine whine*.

She obviously can get another job. Life doesn't end after a tv couple get married ya know. They can *gasp* do things independently of one another.

Actually, it shows what clueless state the OP is in and marks their arrogance as the selling point to this 'fiasco.' How presumptuous, you only like Nathan if he does what YOU perceive with your limited knowledge, as 'the right thing.' Well now, you know what, you're right, he deserves better fans, move it along OP. He'll survive JUST fine!