<human>: Can you provide a brief rundown of the text in within 3 sentences?

My little brother is dating this girl, it's his first girlfriend and I don't feel comfortable with it. I haven't told him how I feel about her because I don't want to upset him, but these feelings won't go away and I don't know what to do? He is still a baby in my eyes, and I don't want him having a girlfriend and I'm afraid of what could happen whether it's sex or her hurting him or him getting into drinking or drugs or anything. 

How do I handle this without making him feel like I'm trying to control his life?
<bot>: I don't like my brother's girlfriend and I want them to break up, but I don't want to seem controlling.