A pair of E. Bluebirds came to my bluebird house she made the nest,after it was made they just left

I had a male eastern bluebird come to my bluebird house a few days later a female appeared. She started making a wonderful house for 7 days. Yesterday the male came and sat all day and she did not show up until late evening for just a few seconds and today nothing. I had gotten so excited about the fact that I was going to have a bluebird family and now it seems that is not going to happen, why would she have made the house and then go away. I did look inside of it, but they did not seem to mind since she worked on it for 7 days.

Maybe because u looked at it they could sensed that u had seen their "hiding" place and actually looked inside it.