Kalavani Sirukki (2018)

A high school boy falls for his teacher and wants to marry her. The teacher is well aware of his intentions and keeps him on a leash. However, fate has other plans, and she ends up marrying the father of the school boy. Now in the same house, he renews his efforts to win her affections, and eventually does. Then she gets pregnant, but both the son and father claim responsibility. The rest of the movie follows the tensions and cracks in the family as they accept the situation and work around it.