Castle Season 5 finale left fans with the one Castle-Beckett cliffhanger that can be bigger than last year's season ender. Series creator Andrew Marlowe has earlier teased fans about some serious questions to be asked, but the story development still managed to level up the thrill. Now, guess who said, "You don't let people in."

Spoiler alert: This review contains major spoilers for those who have not watched the Castle Season 5 finale, "Watershed." Read at your own risk.

A year ago, Castle Season 4 finale had Beckett and Castle walking off in separate directions, only to pull them back in together towards the end. This season, fans feared a break-up coming as Beckett got a job offer way outside New York - very far from Castle. (And avid viewers know Beckett once ended a relationship due to a long distance situation.)

This year, Castle Season 5 finale fades out after Rick Castle proposed to Kate Beckett. Marlowe was telling the truth, after all. Questions were asked.

"Are we moving forward? Are we not moving forward?" Marlowe said these are the questions that play out in the finale. "I think that we look to explore some of those questions which are very human, very natural questions at the point in the relationship where these two characters are."

Castle Season 5 marks a year of Castle-Beckett romance - from the daring rainy night knock on the door up to the proposal. Even the 'Iron Gates' has acknowledged and even expressed support for their relationship. But as much as the writer and the detective are trying to be grown-ups with each other, some old baggages linger.

For instance, Beckett couldn't bring herself to ask Castle to sit down and really talk to her. He would die with her in a bomb explosion; she should know the man's absolutely serious to be with her. She still has trust issues. Ironically, some viewers knew problems were on the horizon when Rick's ex-wife Meredith told Beckett why they divorced. Meredith said Rick wouldn't open up to her.

When Beckett apologized to Castle for not letting him in on her career plans, he tells her: "It's who you are. You don't let people in."

The Castle Season 5 finale is an effective way of keeping fans interested at least until the beginning of next season. The story developments unfold naturally, as Rick and Kate are both emotionally stunted, anyway. The proposal is not a big shocker, but as much as fans love the couple, they are divided on whether the two are ready for marriage. This alone keeps the interest high for Castle Season 6.

Castle Season 5 Quotes

"What if all we were in love with was the dance?" - Beckett
"Whatever you decide ... Katherine Houghton Beckett, will you marry me?" - Castle

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