I've recently noticed some behaviors that may be sexual. At first, I was confused and had no idea what he was doing until my mom pointed it out one day. It all started with this thing he would do while he's on my finger. He'd start spreading his legs and acting all off-balance. I thought he needed to poop at first, but he wouldn't get off my finger if I offered him the perch, so that was out. Then he started sitting halfway in my shirt and rubbing his bottom on my collar and grunting. That was when I realized he was using my shirt to stimulate himself. I also realized that he was trying to rub himself on my finger before.
I'm not really sure how to handle this. Skittles (

) has actually become much less bitey and better with new people in the last few weeks, which is when this whole thing started. I don't encourage this behavior, but I don't discourage it either.
How should I handle this? I know it isn't a good thing for a bird to think you're it's mate.