I think that legitimate relationships can definitely exist in middle school.
In 6th-7th grade, when I lived in California, I dated a girl until I moved. After getting over that, I developed what ended up being a great relationship with a girl in 8th grade until I forgeted everything up. Thus began the manwhore period, where I ended up dating 5 girls in one year, in 9th grade.
Currently, in sophomore year, I'm holding a very stable relationship with a girl I've known for quite a while now. We've been dating since July, so that brings us to about what, 4, 5 months or so?
anyway yeah, relationships can totally exist previous to high school.