It is pretty clear who wears the pants in the Stannis / Melisandre relationship. Have you noticed how Melisandre conveniently works sex into pretty much every "ritual" she gets involved with? "Oh no, honey, I have to tear his clothes off and hit it before I put the leeches on or it won't work." "Okay honey, I trust you." Damn. We don't blame Stannis for lacking the stones to stand up to Melisandre. If a lady says shit like, "I've slaughtered many lambs and none have seen the blade," we're likely to respond with a "Okay honey, well, I'll be in the den watching the game if you need anything. Have fun."
Stannis reaches whole new levels of weak when he goes down to the dungeon to seek solace from Davos while the Onion Knight is trying to learn how to read. Stannis is all "I'm sorry about your son," and "So, I'm debating whether or not to kill my nephew." In short order, they are two Bud Lights shy of a commercial about how sometimes you just have to have some male bonding time. Then Davos ruins the bromance with a classic Davos moment when he quips, "You could have freed me yesterday or tomorrow. But you came to me know before this boy is put to the knife because you knew I'd counsel restraint." Real talk.
It's hard to imagine Stannis being king of anything.