she sees Ganga just like she saw Gauri ...a man snatcher.
the problem we viewers are having is that we refuse to understand that only we see thing from backstage. the thoughts, conversations, intentions and actions.
the character only works on what they see physically.
personally i dont like how things are going but i dont blame Sumitra for that. th problem i have with Sumitra is the fact that she really thought its great for Jagya to marry Anandi's sister-in-law. and again the way she talks to Ganga without...even thinking about how she physically saw Ganga being treated by her-in-laws and ex husband. she did even talk like that to Gauri.