I can see that many here see this as a natural progression and you actually are spot on. This show started on the premises of friendship and the writers have to explore the friendship before moving on to the next level.
We have seen that Shravan loved Sumo as a child, possibly loves Sumo still. He wanted to take it to the next level then, and possibly, wants to do the same now. But where the young Shravan, immaturely and with all the gusto and enthusiasm that youth brings with it, confessed his feelings and expected a response, the older more mature Shravan knows there is a time and place for everything, including emotions, to unfold.
Yesterday, what transpired between the two was an understanding that was broken by misunderstandings, time and age. So, yesterday, the two of them mended the delicate fabric of friendship. Yes, Sumo anticipated something else. But what? There was an idea planted in her head by Preeta, who did so without completely understanding Sumo's relationship with Shravan. But is Sumo romantically inclined toward Shravan? No. There is an attraction, but that attraction could also stem from the depth of love she feels for her FRIEND Shravan, who with age has become physically desirable.
I don't read anything romantic in Sumo's disposition yesterday. She was confused and did not know what to expect. She was disappointed, not because he wanted to renew the friendship, but because he confessed to have tried with all his might to forget that friendship, a friendship she holds dear. She promised not to leave him, not romantically - when he asked to let the past rest and move ahead, she saw in him a goodness that had always been there - something that the young Sumo recognised and saw but did not quite appreciate. The young Sumo, in her immaturity took his goodness for granted. The older Sumo, saw the goodness and marvelled at her young self that abandoned him when he needed her. And there she comments on how anyone could leave his side, because he is such a good person and promises to always be there for him, as a friend. All the time, it is about realising that he is indeed a wonderful wonderful person.
I think the next step would be to discover her feelings for Shravan and fall in love. I don't think she is in love yet and to show that she is would break the flow of the story telling. And so, Im not sure if I'm comfortable with Preeta putting ideas in her head - because why would Suman want to find out if he loves her. Does SHE love him? And if so, when did she fall in love?
I think the writers should take their time and show Suman falling in love, without actually rushing the process. This is my take on the whole thing!