There was no look of shock or surprise on Gauri's face when she read those papers. That look of determination tells me that Gauri knew abt the Shiv-Ips jodi...probably saw them in that passionate clutch today or even read that embrace in Calutta correctly.
Her idea was probably to wait and see what happens to herself. If she died, well Shiv would marry Ips. If she didn't, then she would divorce him.
I guess that's what happened today.
Can't explain the C-night, though!