Well, sure, let them play around with the idea of having a relationship with the opposite gender. It's preparing them for when they're older, more than anything (little girls play with dolls to get prepared for caring for children, the same way little kids play with mini relationships to get used to the idea of more mature relationships when they're older)
As long as the most "sexual" thing they're doing is kissing on the cheek, then it's all good in my opinion.
Besides, if they're not allowed, they'll just hide it (believe me, I know XD)
By allowing a child/pre-teen to be involved in something that they care about, they benefit that much more versus someone who doesn't or can't be in a relationship. Let 7-yr olds have boyfriends or girlfriends, let a 11-yr old explore what it means to love somebody. Besides, it is cute.
It doesn't really matter if it is right or wrong. It is their choice if they want to have a relationship. It's all for experience. It is a part of life so why not explore it? It think that seeing a young couple is cute and if they're happy then let them be happy. I mean other people can't decide if they cannot have a relationship. Maybe if it dangerous like if one of them is abusive, but that's all. Let them be happy and explore relationships.
I agree that kids need to learn how to interact with the opposite gender, but kids and preteens don't have the maturity to understand what goes on in a real relationship. They need to focus on what they are going to do with their lives, what career they will pursue. Relationships are a distraction for the young people. Love is not fairy tale, it takes hard work, commitment, trust, and love. I believe kid should be kids for as long as possible because you are only a kid once. Relationships are for responsible adults. Plus, it saves them from being heartbroken so early in life and from becoming angry and bitter adults.