the first thing most people shriek is TOO YOUNG FOR BOY/GIRLFRIENDS.
it's also the best way to make having a romance unbearably exciting.
your wild and boy crazy granddaughter may well have a very different view of what 'having a boyfriend' looks like than you envision.
neither of my boys ever went through a 'girls are icky' phase. they both had girlfriends in kindergarten, and longed for them wistfully during awkward phases of elementary school. in kindergarten it meant sitting next to a girl at story time. by 5th grade they might write each other notes or hold hands.
if you're an authoritarian, by all means lay down the rules and impose harsh consequences for transgressions. i think it will backfire badly, but there are all sorts of methods of parenting and maybe it will work. but allowing young children to explore adult behaviors (like playing house or astronaut) does not mean you're helpless and uninvolved and contributing to immature sexual experiences. a parent (or grandparent) who has thoughtful age-appropriate discussions with kids about what romance entails, and later what sex is all about, and realistic (not hysterical) talks about the reasons to hold off on physical intimacy until later tends to have better outcomes in my experience.
you don't say exactly what the issue is here. is abrina upset because you or her mother have forbidden her to have a boyfriend? or because she's interested but none of her male peers are? are you raising her?
the 'desperate for a boy' sounds like a tragedy waiting to happen. my approach would not be to forbid boys, but to make sure that i stayed part of the conversation and was accessible for questions or worries.
khairete
S.