My girl is currently unspayed, but is being kept in a separate space from my boys now that she's ready, as she became a relentless humper overnight. They can all still see and smell each other and they're licking through the bars, which makes me feel evil, but the boys were getting a bit fed up and Cloud already puts up with it from Bilbo - but at least he doesn't keep running back to try again once separated. Bilbo was quite funny though, because he just kept running away, He's always the one to do the humping between the two boys :roll:
In short, it's possible. Pooka bonded really easily as a baby, but I was watching like a hawk for when her behaviour changed, and I admit they were still separated by the pen when they weren't supervised for that reason. I will add though that anticipating a spay is horrible for me, I'm so nervous!