Came across this tidbit from BBC:
Saudi authorities consider Valentine’s Day, along with a host of other annual celebrations, as un-Islamic.
In addition to the prohibition on celebrating non-Islamic festivals, the authorities consider Valentine’s Day as encouraging relations between men and women outside wedlock – punishable by law in the conservative kingdom.
However, people in love are pretty resourceful:
The Saudi Gazette reported that some people placed orders with florists days or weeks before Valentine’s Day in anticipation of the ban, which is a regular occurrence.
“Sometimes we deliver the bouquets in the middle of the night or early morning, to avoid suspicion,” one florist said.