The stylist is being looked after by family and friends as the band's fans continue to vent their despair online.
A friend tells PEOPLE that Briana has gone away for a few days to escape the scrutiny. As soon as the news was revealed on Tuesday evening, #OhNoLouis began trending on Twitter – and the discussion among fans hasn't slowed down.
"Briana is staying away from home for the moment; she's a private girl – she doesn't even have any social media. Everyone's hoping she can have a smooth pregnancy in peace. That's the most important thing for everyone right now," the pal says.
"Briana and Louis could not be more excited. Louis is looking forward to finding a new house and setting up a home in Los Angeles near where Briana lives."
As PEOPLE revealed, 23-year-old Louis' mom Johannah and stepdad Dan met Briana and her family during a sun-soaked lunch over the July 4 weekend. Both families are extremely excited about the new addition, due next early year.
The families have been to the ultrasounds, and Briana has grown steadily closer to Johannah, a midwife and mother of seven who gave birth to twins, Ernest and Doris, only 17 months ago.
Meanwhile, PEOPLE can reveal that Louis told his former long-term girlfriend Eleanor Calder, with whom he split in March, the news before it was made public.
"Eleanor knows and she's fine," the friend tells PEOPLE.
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