So they wanted to nest and now that they have a nesting box, have stopped

You must be patient enough to wait when they like to nest. These birds are sometimes like humans also. They take some time to adjust and be familiar with their own "house". However if they don't give any result with the nesting box that is prepared for them, try to provide another form of nest. I don't know if you try to make nest out of a coconut. Just take out the shell, clean the inside especially the root-like elements that come out when you take the coconut shell. After cleaning, join it together by clamping it with a small wire, and make a small hole at the side enough for the bird to pass through. Then, hang the nest in one of the corners of the cage...

LOL We have one nest that is out on our porch that has been there since we moved in two years ago and the sparrows nest in it every single year. I've had a heck of a time keeping it up there with the maintence guy too. **AT PEACE WITHIN** ~~STAND STRONG IN YOUR BELIEFS~~

I think they will come back. They go away for a while when someone messes with their territory. they will get used to what you have provided for them most usually and come back though.

The mating season is over. I still have my nesting box on my bird cage sometimes they will go in and make a nest but don't do anything. You might want to take out the nesting materials and let them make their own and see what happens.