What function does Jose Trevino serve in the novel Like water for chocolate?

Jose Trevino is the once lover of Mama Elena, the ruthless matriarch of the ranch. Once Tita, the protagonist discovers the correspondence between Mama Elena and Jose, she realizes that Mama Elena did not always follow the traditions that she so strongly enforced. Since Jose was a mulatto, Mama Elena could never be with him. However, Mama Elena does have an affair with Jose, and Gertrudis is born as a result of this. The presence of Jose reveals that all the characters of the story are susceptible to the power of love, even Mama Elena.