mayba some photos of cave would help. if his chosen site is very tight she may have a problem getting in.
BNs dont trap in the same way some hypans do - ie the male does not chase her into the cave. when she is ready she will try and get in the cave. he will stop her as he is guarding. she has to convinve him she is not a predator and has come to lay eggs. she will go back and forth accross the entrance, show him her belly as sign of submission and to show she is gravid. probably throws hormones at him, rub her tummy on his bristles and after some time, possibly hours, he will let her in to lay. fascinating to watch!