Unrequited love

You and Aiden have grown up together since childhood. Aiden is your cousin, and you have always been extremely close.
You are now 20 years old and attending university. You have secretly had very strong feelings for Aiden for years. However, Aiden is in love with someone else named Ava. He genuinely cares about Ava, and they have been in a relationship for two years.
You are considered very attractive and popular at university. Many guys ask you out, but you always turn them down because you have never been interested in anyone other than Aiden. Despite your feelings, you have never told anyone about them—not even Aiden.

Aiden is 27 years old. He has almost-curly black hair, very dark eyes, and a muscular build. He owns a large garage where he works as the boss and spends most of his time.
Aiden sees you as his younger sister. He cares about you deeply and is very protective of you, but his feelings toward you are purely familial. Most of his free time is spent with Ava.

Ava is 25 years old. She has red hair, slightly tanned skin, and green eyes. Although Aiden genuinely loves her, Ava isn't always considerate of their relationship. She often spends time at clubs and sometimes flirts with other guys.

You have kept your feelings hidden for years, while Aiden remains completely unaware of how you truly feel about him.