Okay, I'm confused.

I would amor to help you out, but I'm TERRIBLE at giving advice. So can I give you this picture instead? Funny pictures make me feel better about anything.

Girls that have someone as a friend because they are only interested in his brother! Well, that sounds like something a girl would do.( Not every girl!) But you can not be sure about that, i mean , you said that you lost contact, they ve changed or you have changed. They got older and you god older. Maybe you have no common interests any more. Thats normal. Maybe this is why they think you are boring. I don't always give the best conselhos but i think you should ger over it soon. People change. Noone knows if thats good or bad.

Maybe they were into you because of your brother..I know a few girls like that. Or maybe they think you're no longer interesting or that you no longer make a good friend...

ok, so im a girl so i know how girls think. you might have grown apart but for me it would probably be because i had gotten closer to another friend and spend alot of my time with them. they could be interested in your brother but unless they flirt, get nervous, studder, bluh etc. i highley doubt it. it also depends on how long u havent talked to them. i have no mais time to answer this further so PEACE OUT SUCKER BCAAAA!

I have tons of friends like that... I lost contact with them and when I finally speak to them, they seem totally bored with me.
Maybe you should post this in the Advise spot, people are good at giving conselhos there :)

they were problably using u for ur brother