So 1st of all ,she was all the way happy with Randhir's past because she had nothing to do with it ,she just felt ignorant because randhir hided the past from her .She was neither in secured nor jealous.
Right now ,she is feeling hurt /insecured because she can see randhir is hiding something from her,something from himself.Its evident that Randhir still feels for Sanyukta and Sanaya can feel it .
That is why she confronted her about his feelings.And people made it issue of insecurity.
Moreover a person you know for 1.5 yrs,be it friends,lovers,cousins or whatever it is ,he/she is acting a bit indifferent ,hiding something from you.Dont you have the right to question that person?To bring things in the right track? you definitely have...
And so in the case of Sanaya .She knows Randhir and can feel everything that what's going on in his mind .
done with my post
now need valuable comments