Here is a list of Tamil Movies that were about complex relations
Vaali dealt with a love story where a deaf and mute Ajith is in love with his sister-in-law.
New was about the transformation of 8 year old boy into a 28 year old adult.
Enthiran spoke about the love a robot has for a human.
Vidukathai revolves around the relationship between a young woman and a man who is in his forties.
Kalki discusses about how an abusive relationship leads to multiple issues.
Father Rajinikanth sexually assualts Saritha. Son Rajini then makes a shocking revelation. Turns out that the girl who the father assaults is actually his daughter-in-law.
Thappu Thalangal talks about the relationship between a commercial sex worker and a thug.
The relationship between Vijay Sethupathi and Pooja Devariya was a very bold one.
Goa spoke about the homosexual relationship between two male characters.
With a good performance from Sangeetha, this movie revolved around how a married woman happens to develop love for her brother-in-law.