By the way, if you noticed, Patralekha was still in a "guilt" mode even after one year of Sai's death.
PREDICTION
So it can happen, that the family got Patralekha and Virat married so that two broken souls can come together and knit a "family life" for a young boy and in the process, get their souls healed.
Bhavani might even suggest that since they were friends before, it would be easier for them.
That thrashes two theories that are circulated - fake marriage and mental illness.
Also, since Patralekha ka koi plan nahi tha (looks like till we get the marriage question answered), she will start getting obsessive now. But now, she will be an obsessive wife who will keep apart Sairat.