(Scholars beware the difference between bhāva and bhava. It changes the meaning entirely.)
Antarabhāva is sometimes likened to the mind-state of the caterpillar in the cocoon. Human souls enter antarabhāva in preparation for a human birth. Depending on the soul, it may take years to fully awaken after a human birth. At death of the human body, soul enters into antarabhāva again to begin the journey away from Earth consciousness. The soul awakens into a new soul reality after a while. This is a time for reflection, processing the past lifetime, and for future dharma and karma to be calculated.
In the sacred sensuality tradition, devotees learn to enter antarabhāva during sleep, meditation, sex and certain spiritual activities. Antarabhāva is also a place where Wayist teachers in the esoteric tradition meet with geographically dispersed devotees.
Over the last 3,000 years several traditions have developed around this concept. As human nature goes, today one can read about hundreds of different names, labels, definitions and supposed qualities of different awareness states in this context. There is no need to label and name everything, it complicates life. Suffice it to know that antarabhāva exist and it changes in intensity as it must and when required. It is a supernatural function of the soulsphere and it works very well just the way it is.