I see almost all had made some mistakes in this situation... but not all mistakes r in the same level... absolutely Taani's fault is uncomparable to other's mistakes...Thus Vishake's mistake can be considered as nothing when it is compared to Taani's...
All guys did mistakes but they did for good intentions... whereas Taani was the only person who made mistakes for even not-good intentions... using others, specially ur brother, to reach someone who doesn't even care about u, doesn't love u!! I think stupidity can't get more this!!
This makes me wonder... a person who can hurt/cheat her close ones, her kind brother, for the sake of someone she barely knows... how can she be that faithful, lovable, selfless to Rey when he falls for her if she couldn't be like that for her own family?!!!
For me, this completely doesn't make sense and I feel sorry for Rey to be involved with such weak relationship...