They did come close, some people get stuck at trying to get them to spawn so you should be proud of yourself. You have a nice set up, so she was probably just too young.
Females can lay hundreds of eggs, and if everything goes right, most will be fertilized. This is a lot of babies to take care of, but because bettas are conditioned before spawning, the male will be energized and healthy enough to care for so many eggs and fry, even if he is tending to them all the time. So he will have time for them :)
That is why it is so important to condition (also for good quality fry).
I am not a breeder btw, but I have been doing research as I plan to one day.