The 36-year-old actor viewed his 'Game of Thrones' co-star as one of his best friends so although it wasn't "hard" shooting scenes in the final season of the show where the relationship between their characters Jon Snow and Daenerys Targaryen turned romantic, they often got the giggles and ultimately found it quite "weird", reports femalefirst.co.uk.
Harington, who is married to Rose Leslie, another actress from the HBO fantasy drama series, told Candis magazine: "It wasn't hard to kiss her, although I used to pretend it was. The thing was that we were best friends over a seven-year period before we had to kiss, so it did take a while of looking at each other and laughing before we could get into it.
"And there was definitely an element of weirdness if she, Rose and I would be having dinner, and Rose would say, 'So ... how was your scene?' And we'd say, 'Yes, well, it was good...' I don't think it's ever comfortable."
Meanwhile, Kit previously revealed that he broke down in tears when the show's ending really dawned on him, despite being convinced he'd be able to be "cool" about it.
During an appearance on 'The Graham Norton Show', Harrington shared: "I was determined to be cool about the end and decided that when people came up to me and said, 'Are you Jon Snow?' that I would say very calmly, 'I used to be'. When I left the set for the final time I was very emotional, and when a girl came up to me and asked the inevitable question, I broke down and cried, 'I used to be!' She backed off pretty quickly!"