I think it was a matter of GRRM not knowing how an 8th grader would think. GRRM assigns the thought processes of a 35-yo former stripper with three ex-husbands to Dany and (much much worse) Sansa, who are 13 and 11. There is a degree of sophistication in thinking of your body and your sexuality as a product, as a tool to use to get what you want from males. Dany is actually less egregious here than Sansa because Dany has been drug around by her sicko brother and has been exposed to leers from creeps for a while now. She is pre-sexual, but she gets that grown men want things from her and what those things are, and she sees the potential. Sheltered 6th grader Sansa should not be the same, but she is.
But, GRRM is a mess on the ages of the kids. Robb is 14 with no miltary experience, leading armies. Tyg Lannister was out there slaughtering grown ass men in the War of the Nine Kings, including members of the Golden Company...at age 10. Rhaella and Ser Bonifer Hasty supposedly had this great epic romance prior to her marriage to Aerys...which occurred when she was 12. So...just in general, GRRM doesn’t have kids and possibly doesn’t know any, so he just knows nothing at all about child development. You have to just accept it.