My brother's girlfriend

She's very sweet and she's good for him. I'm happy for him! Yet I can't help but resent her. I don't know why. I don't know if I'm jealous or what. My family loves her. They don't know my boyfriend yet. Him and I haven't been together long, but then again neither have they. My track record with chosen mates isn't a very good one and my brother's isn't as bad as mine. Am I a bad person? What is wrong with me!? I'm such an ass.