If you are on a Non-O Visa you are on a 90 day stamp so do not do 90 day reporting so your finances are too late for your 12 month Extension of Stay application. You will be denied the extension, will be required to leave Thailand then re-enter and use your banked money to apply for a new Non-O Visa (90 day stamp).
What Visa are you on or, more likely if you are doing a 90 day report, Extension of Stay based on what? There is no financial requirement for 90 day reporting and no 90 day reporting if you are on a Non-O Visa so which is it?
So you need to be out of the country long enough to apply for and get the Tourist Visa issued (see the Thai Embassy website of the country you will be visiting for timelines)
If your ME Non-B is still in date/valid on your return from Europe to Thailand you will get a new 90 day stamp. If your Visa expires when in Europe then purchase a single entry re-entry permit to keep your current 90 day status live on your return.
Thai partner means not wife (I assume) otherwise your solution would be easy, a Non-O marriage Visa giving you 90 days on entry followed by a 60 day "Visit Thai Family" extension.