Heather Watson and her doubles partner fall foul of the third seeded Italian duo.
Watson and Boulter had cruised through the earlier Olympic matches at Roland Garros, despite the odds being against them.
They beat the Germans Angelique Kerber and Laura Siegemund in straight sets, 6-2 6-3, on Tuesday, 30 July.
They reinforced their dominance with another straight sets victory over the sixth seeded Brazilian duo of Beatrice Maia and Luisa Stefani, winning 6-3 6-4, on 31 July.
But the third seeded Italians, Sara Errani and Jasmine Paolini, undid this progress in little over an hour, winning 6-3, 6-1.
Yesterday marked the end of an era for Andy Murray.
The two-time Olympic singles champion lost alongside Dan Evans in the quarter-finals in Paris.
There were tears as he was given a huge send-off by the crowd at Roland Garros.

Guernsey deputy backs pavement speed limit
Plan to reduce violence against women and girls in Guernsey and Alderney
Guernsey Airport scaffolding expected to stay for 'a couple more years'
Calls to reduce pavement surfing in Guernsey
Alderney vicar delivers life saving CPR
App launching to tackle loneliness in Guernsey
Guernsey football star Maya Le Tissier scores for England
New Guernsey form aims to identify dangerous road spots