I love this Manga don't get me wrong but I have to suspend my disbelief when I see a married man with a daughter getting flustered for things like this.
It's like you guys don't know that the norms in Japan differ from wherever you're from. "I can't believe..." Well, if you read harem or hentai mostly then I can't blame you.
To quote several Japanese people I've personally met, and some being interviewed on the subject, "That's something I might say on my deathbed to my husband\wife." They really , really don't have that culture, and they consider anime over the top because of it. Watch a Japanese Soap Opera sometime and prepare for a confusing level of Hell. Anyhow, Nishikata is lovey -dovey by comparison, even if he's still a typical Japanese man-samurai about it.