Jesus warned of signs that would lead up to his Second Coming, like the increase in false messiahs, wars, earthquakes and Christian persecution. He also predicted increased pestilences - and in the 20th to 21st we have seen an exponential rise in this - where HIV, Ebola, H1NI and the Corona COVID-19 are simply the latest.
Jesus told many parables regarding the return of a master who had gone away. In all cases, the master returns unexpectedly. In the parable of the faithful and wise servant Jesus says, “The master of that servant will come on a day when he does not expect him and at an hour he is not aware of.” (Matt 24:50, cf. Luke 12:38-39)
The parable about the virgins refers to the Rapture because the groom comes unexpectedly to take only those wise virgins who are waiting and prepared. All the virgins were sleeping – everyone will be surprised at Jesus’ coming. But although the wise virgins were sleeping, they were prepared.