Reiji DID say he has a red line between work and pleasure~
Well thats what he stated to I-19 anyway but didnt stop him from nailing Kongou.
Kongou was VERY clear about her invitation. She deliberately pushed through Reiji's boundaries in order to try to give him something to live for beyond just the war.
...then, may I ask you to make me feel even happier?What?If I could get a day off tomorrow under your authority, I can drink more and it'll be great.We can drink until morning.