Standard Model is advanced version of Quantum physics. It tried to include everything which came in the way while understanding quantum world. It even didn't bother to include even Higgs Boson which was hypothetical at that time. Did they never find gravitation in the way of other quantum interaction.
Note: I know, there were many unsuccessful attempts to add gravitation with SM to make Theory of Everything. My question: Why didn't Standard Model keep gravitation as raw ingredients (with unresolved relationship with others)?