sorry late reply!
. You don't have to be very explicit and detailed with the internal monologues, but a single phrase or something that shares the protagonist's feelings would help a lot.
Another idea I thought of in the following days: With the internal dialogues, the dialogue and a drawing of the protagonist's expression could be displayed at the bottom. Since there's no voice acting, the art and the phrase would convey the protagonist's feelings.
By the way, I apologize if my English is poor; my first language is Spanish.