Apologetic because they were caught. They asked for rosemary cuttings then helped themselves to your mango without you being around. Ripping the branch absolutely indicates a malicious act whether it was out of cluelessness or not. I'm all for keeping good relations with neighbors, but that trust has been broken. If they did this after asking, I would be concerned what they might have done when you were not around. It's a good lesson for all though. Next time, if there is a next time, tell the neighbor you will get them the cuttings yourself. I would not allow them in the yard unsupervised again.