Harman can now begin to realize love to Souma. If, now for the Souma be physically sick because of the poison that had served Preeti, so it is quite possible that Harman realizes his feelings for her to think that she will lose forever. It depends on how far Preeti goes with poison.
Harman gets drunk, and acknowledge that it is in Souma love, and reportedly say it aloud in front of Varun.