I can't say that I can relate, but it was so wonderfully done. I understand how you don't want your brother paying attention to another family rather than the one who's grown up with him for all of his life. Twas beautiful.
I liked this, a lot. The lines were short, and had rhythm which was awesome. Also, I like how there's a twist in the poem, how it's love "In a brother-sister way", because naturally at first the reader believes that it's in a romantic way.
I was also interested by the lack of punctuation, I think it's good in here because it lets the emotions speak more clearly.
Good job! (: