It may be getting too dry. Keep it in good strong light - but move away from any radiators/stoves. Perhaps try it on a bed of pebbles with water in if the house is very warm. They can take a reasonable amount of cold - so maybe move to a hallway or somewhere cooler.

I would think in India the main problems are heat and lack of water.

Irregular watering can easily cause flower/bud drop. Ill-timed feeding can do the same. If it is a new tree, bought while blooming--or moved recently--lack of light could also be a problem.