BRIGG HEAD TO HEAD

Spotted walking down a narrow Brigg street, east to west, head down, a young woman...busy texting on her phone.
Spotted a few seconds later walking down the same street, west to east, head down, a young man...busy texting on his phone
The latter appeared to be listening to music on headphones.
What happened when they had both walked another 25 yards?
We'd headed off by then but hope the didn't meet head on.