Wait until you go to leave. Then the shit'll hit the fan. Still, if you don't care about having to pay a fine or possibly being banned from seeing said fiancÚ here for a year or more carry on with your original travel arrangements. Personally, I'd change them to avoid the risk.
And remember the 90 days includes the day you arrive and the day you leave so no staying for 90 days and leaving on the 91st, that puts you over your limit.
Use the calculator to work out when you'll go over. http://ec.europa.eu/dgs/home-affairs...ulator_en.html
Given the heatwave we've just had I think you may have been better off staying in Texas. At least you have air-con there.
This from an Okie born Brit btw.