The love-hate relationship
The relationship between Thanos and Gamora is quite complicated, to say the least. After all, he abducted Gamora while she was still a child and raised her to become a mighty warrior. However, she never forgot what Thanos did to her and how he abused her.
For Thanos, he had nothing but love for Gamora, the kind of love that an adoptive father would have for his daughter. In Avengers: Infinity War, Gamora exclaims that she’s always hated Thanos’ chair. In response, he sits on one of the steps leading to the seat to show that thinks highly of Gamora.