At the end of "Castle" Season 5, Castle proposed to Beckett. The season 6 opened with Beckett accepting Castle's marriage proposal. Will "Castle" Season 6 end on Caskett's marriage? In "Dressed to Kill," Beckett hesitated when Castle asked if it is okay to move-up the wedding date from fall to spring. The hesitation, however, evaporated at the end of the episode, as she told Castle she is ready to get married to him in spring. The hesitation was more to do with Beckett missing her mother, and had nothing to do with having second-thoughts about Castle as her life-partner.
Andrew Marlowe said to TV Guide that in the episode ["Dressed to Kill"] there is a moment where Matilda is looking at Beckett "like a daughter. I think that keys Beckett to realize she and Castle have been doing all this planning, and that she has this hole that she hasn't acknowledged. It sneaks up on her, but when it hits, it hits like an anvil and it sends her a little bit off balance."
Marlowe did not confirm whether Castle and Beckett will marry in one of the upcoming episodes. However, he said that both the characters are "getting a little more committal."
"... we're watching a process of something that was very theoretical for the two of them at the beginning of the season starting to crystallise," Marlow said to TV Guide. He did not rule-out the possibility of other issues cropping-up in Caskett's relationship, but both of them are sure about where "they want to head."
On whether there will be a wedding this Season, Marlowe said, "I think the characters are thinking about a wedding this spring that would fall within our air dates."
Now that Beckett has a wedding gown thanks to Matilda, Castle and Beckett just need to find a venue and fix a date. The wedding might not be a fairytale one, because there is no "Castle" without a murder investigation. A beautiful bride and a handsome groom running around, trying to solve a case, will be quite a sight.