'Anthaku Mundu Aataruvatha' is a sweet and sentimental romantic tale that attempts to analyze the conundrum that most youngsters face, of how to choose the perfect mate.
Anil (Sumanth Ashwin) is a popular young man who does not want to settle for an arranged marriage. His mother Sujatha (Rohini) is keen to get him married, so he decides to push off to Hyderabad, to escape from the pressure. He has the support of his father (Rao Ramesh).
In Hyderabad, he comes across Ananya (Eesha) and falls in love with her. Ananya is a painter and greeting cards designer and she works for Latha (Jhansi). Anil starts wooing Ananya and she falls for his romantic charms. But Ananya is a little apprehensive about taking the relationship further. Her parents, Sridhar (Ravi Babu), a TV serial creative head and Vidhya (Madhoobala), a yoga expert bitten by the acting bug, keep having arguments and this worries her. Anil sets up a company supplying flowers.
After Ananya expresses her apprehensions, Anil also has similar worries. 'What if our relationship becomes boring and mundane after marriage?' is the question on their minds. They decide to have a secret live-in relationship, to see if they are compatible. They rent a flat for 2 months with a condition that they should not try to impress each other and should be themselves.
Thus starts their life on an unsure note. One night, Ananya has food poisoning during her menstrual periods and Anil, who can't stand people with ailments, after losing a heated argument with her, takes her to the hospital. After returning home, both argue again but reconcile the next morning. Anil and Ananya had sex the previous night and are panic stricken about pregnancy. Fortunately Ananya is found to be out of risk.
The next day, the couple have to babysit Latha's son as she has to depart to the U.S for an emergency. Though they find it initially hard, they get along with child after some days. This happens to continue for weeks and Ananya is annoyed as Anil ignores her as he is indulged in the baby's care. As Ananya is about to leave for Mumbai for a painting exhibition for a week, she comes to know that her mother is going to divorce her father after winning an award for Best Vamp in a serial aired in Sridhar's rival channel.
After Latha returns, Anil vacates the flat when Ananya tells him she wants to put a stop to their live-in relationship. Meanwhile, Anil's father comes to know about the betrayal done to him by Sujatha before their marriage which he shares with Anil.
Anil's father loved Shyamala (Pragathi) but their marriage was opposed by Anil's grandparents. By that time Sujatha, who was in love with Anil's father coerced Shyamala and her family to leave the town, paving way for their marriage. Now Shyamala is in a hospital in Hyderabad and the duo go to the hospital and are shocked to find out that the donor of the required liver tissue is Sujatha. She did it as an act of repentance for the sin of separating them, raising her level of respect and love in the hearts of the duo.
On the other hand, Sridhar is filled with sorrow as Vidya left him but to the surprise of Sridhar and Ananya, Vidya returns the next morning after hearing about Anil's life with Ananya in the past 2 months. After gaining acceptance from both families, an emotional Ananya reconciles with Anil.