MNA Fatima Houda Pepin is no longer with the Liberal caucus and will now sit as an independant.
The MNA for the South Shore riding of La Piniere is at odds with her party over the restriciton of religious attire in the civil service.
Houda-Pepin wants a restriction to be placed on police officers, prison guards and judges, while the rest of the party wants no ban at all.
"I've spent about 30 years fighting fundamentalism. I can not say from both sides of my mouth that the door is open for everyone and at the same time that I am fighting fundamentalism," says Houda-Pepin, who had sat for the Liberals for 20 years.
The Liberals say they wanted her to stay, and Houda-Pepin says she wanted that as well, but Couillard says he can not keep an MNA who disagrees publicly with one of his party's core values.
"It's not a happy event, but it had to stop," says Couillard.
The full details of the party's new official stance will be released tomorrow.