I wanna enjoy the fluff, but why the heck is a married dude worried about an indirect kiss with his wife?!
My suspension of disbelief is willing to accept normal dude + assassin wife with manga-level assassin powers, but the whole being shy thing is where I'm drawing the line.
If you wanted them to act like people on a date for the first time, don't make them married, but just have them dating or something.