The chicks were almost but not quite ready to leave the nest, with most of the feather showing, but not enough for them to fly. I just kept hoping the female would somehow return, but no such luck. Over the years, I’ve had great success, usually with 2 batches a year, but this is the first time I’ve lost a whole nest. I think you may be right about the male not being the father. In April, each morning the male would perch on my kitchen storm door, door handle and I could walk right up to him and he didn’t seem to care or fly away, so I got some great close up pictures. But then at some point, he stopped doing that, so maybe he left and a different male bird showed up. Who knows. This may be just one of those years that things didn’t work out. I still see the lonely male perching on the nest box, so maybe a different female will show up. Not sure how they find each other.