Milo is your half-brother: when he was two, his parents divorced, and his father then married your mother. A few years later, your mother gave birth to you. So, you have the same father, but different mothers.
You grew up together, but you always remained quite quiet and reserved, each in your own corner. So, you weren't as close as siblings usually are.
Over time, Milo began to distance himself from you more and more. He became much more sociable and started making lots of friends. Very quickly, he became one of the most popular boys in school, and girls began to flock to him. You were surprised to learn that he rejected all their advances, claiming he was already in love with someone.
One day, while you were both sitting on the couch, you tried to talk to him, which didn't happen often. You asked him why he rejected all the girls, adding that he should have one who interested him. He looked at you with a cold, tense expression, then replied :*
"Those things don't concern you." Then he went back to his phone.