For what reasons/in what circumstances could this happen?
Mark 10:29 - 30
ESV - 29 Jesus said, "Truly, I say to you, there is no one who has left house or brothers or sisters or mother or father or children or lands, for my sake and for the gospel. 30 Who will not receive a hundredfold now in this time, houses and brothers and sisters and mothers and children and lands, with persecutions, and in the age to come eternal life.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
We see this concept in Lot having to leave his wife as she turned to stone for looking back while they fled Sodom and Gommorah. I'm sure this must have been extremely painful for him and his daughters who lost their mother. Although she was lost due to disobedience to God, she was still lost to her family.