I think that's because under certain severely-outdated laws here, foreign women wed to Thai men are technically considered to be "adopted" rather than married. Don't quote me on this though. Just what I heard.
I wonder if they can revoke your citizenship via marriage following a divorce? 🤔
I was in a similar situation in 2013. It's true, they will no longer add pages to your passport, but a new passport takes about two weeks to process. When I had a similar problem, the US embassy issued me an emergency passport. It's processed quickly, valid for only one year, and you have to cancel it when your real (new) passport is fully processed by the embassy after about two weeks.