I had a couple of boyfriends when I was twelve/thirteen. Both were older than me and in both cases we went out for oh, about three weeks. I was heartbroken when they broke up with me.
I am still friends with both of them 25 years on although from a distance as we now all live in different countries. One of them I suspect is gay although sadly the country he lives in it is not as tolerated so I suspect he has never felt able to come out.
I had two boyfriends who were five years older than me - one of them when I was fourteen. At the time I suspected his mother didn't like me, but in retrospect I suspect she was concerned because I was so young.
I never had sex until I was 21.
I think that forbidding "relationships" is a bad idea, because in truth unless you forbid your children from having friendships with children of the opposite sex you won't be able to prevent attractions from developing. And if you've forbidden them from going out they'll find a way to do it anyway.
Being attracted to one another is part of growing up - it's normal, and just because they're attracted to one another doesn't mean they're having sex.
It's better to be open about, and supportive of the friendship/relationship because if it does reach a more serious/concerning stage you're more likely to be more aware than if you've forbidden them from seeing each other and they're doing so behind your back.