Way too much strawmaning going on here. It seems that if you oppose some pairings in ASOIAF, you're either not accepting romance or refuse to accept girls as sexual beings. While, in fact, there are good arguments for this opinion.
The thread title mentions Dany's age, so I'll start with that. No matter how well it's written, no matter how much actual hints GRRM put into it, I'll always find these romances and implied romances between girls entering puberty and adult men creepy and inappropriate (I'll refrain from mentioning word starting with -pedo and ending with -philia). Such pairings deserve the exact same opposition as if they were in real life: namely that they can't be a relationship between equals. Adults are by definition more mature, smarter and more stable then children. And before anyone accuses me of denying complexity of children or children's characters - I'm not, I'm just stating a simple fact of biology. Compare 13-year old self to your adult self and you'll see what I mean. All in all, if an adult is truly mentally at the level of an 13-year old, that adult has a problem.
Second factor is that it's unrealistic. I know plenty of people in their twenties, being one myself, but I don't know even one who is sexually or romantically attracted at boys/girls half their age. And yet, it's ever-present in ASOIAF-verse: Sandor, Tyrion, Petyr, Illyrio, Viserys, Drogo, Raff, random men in Braavos... you name it. Perhaps GRRM truly wrote a fiction where human behave like humans in our world, have some psychology and biology as humans in our world, and for all intents and purposes are exactly like humans in our world (which is one of the best things in the series, but I digress) with the sole exception that their sexuality works differently and it's normal be be attracted to pubescents. Maybe that's the case, but I still find it creepy.
The other thing is how lot of these relationships come of as (or start as) flatly abusive. For example, this Dany/Drogo supporting quote, somehow conveniently fails to mention this:
Even the nights brought no relief. Khal Drogo ignored her when they rode, even as he had ignored her during their wedding, and spent his evenings drinking with his warriors and bloodriders, racing his prize horses, watching women dance and men die. Dany had no place in these parts of his life. She was left to sup alone, or with Ser Jorah and her brother, and afterward to cry herself to sleep. Yet every night, some time before the dawn, Drogo would come to her tent and wake her in the dark, to ride her as relentlessly as he rode his stallion. He always took her from behind, Dothraki fashion, for which Dany was grateful; that way her lord husband could not see the tears that wet her face, and she could use her pillow to muffle her cries of pain. When he was done, he would close his eyes and begin to snore softly and Dany would lie beside him, her body bruised and sore, hurting too much for sleep.Day followed day, and night followed night, until Dany knew she could not endure a moment longer. She would kill herself rather than go on, she decided one night … Does this sound like a happy relationship at this point? Does this look like consensual sex to any of us. To me, it just seems that Drogo has sex whenever he wants and completely ignores Dany's pain and wishes. Replace Drogo with Robert and Dany with Cersei and you basically get a description of royal couple's sexual life which Robert (rightfully) gets lambasted for. But here, such rape and abuse is not a dealbreaker, it simply an obstacle Dany should overcome. You see, if you could only ignore this "abuse" silliness and suggest your husband a different sex position, everything will be fine. He'll even start to fall for you. Attagirl. And frankly, I find this very disturbing, to say the least.