i think it's pretty normal to tweet those stuff when you're down or stuff. so i dont see why netizens would speculate abt disbandment of the girls having bad relationship with each other/company.
i for once can see the bond between the 6 and soon to 7 members.
i can understand how jiyeon feel, at her young age, she has to experience so much more than a normal hgih school student would do, no doubt she will feel stress out.