Those fans aren't thinking about her personality or about circumstances where marriages don't work or about how great they are at co-parenting - they're just considering her actions.
Before, they disliked her because she was the one who asked for divorce and "how can you ask for divorce from Hrithik?". Plus, like RTH rightly said, Hrithik seemed pretty tormented for a significant while after 2013, so fans would blame Sussanne as the person who's at the root of Hrithik's turmoil since they obviously won't blame him. Didn't help that the divorce sparked the rumours about Kangana, the woman who made his life hell for a while.
But currently, it's because "how can you choose Arslan over someone like Hrithik"
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