You can reveal more about your character's feelings by
a) varying your sentences
b) using dialogue
c) borrowing from established literature
d) repeating important actions

You can reveal more about your character's feelings by using dialogues.

Dialogues give the writer the opportunity to show how each character reacts in different human interactions and social situations, the reader can see the feelings of a character emerge from the lines even when they don't explicitly say it, context plays a big part of what we communicate with stories.

Variyig your sentences can show a big range of vocabulary or structure but it doesn't necessarily show deeper details of the characters.

Borrowing from established literature imitates the develope of characters to previously planned material.

And repeating important action might emphasize details but not actually bring them to light.

just say it's your friend did it and you had no idea?