@IRonMaN is what we curmudgeons call "Minnesota nice," which means that if he hears someone at the barber shop giving out incorrect information to three other customers, he'll still chip in to buy the guy a shave along with his haircut.  Unlike me, he is not concerned about sludge on the Internet.  If I see something that might mislead the next ten readers, I will do what I can to stop it from oozing that far, even if the befuddled originator is hopeless. 

If anyone -- today, or in the rest of this century -- really wants to know the IRS position on this question, it's right there in Pub 555:

"In some states, the marital community ends when the spouses permanently separate, even if there is no formal agreement. Check your state law."

https://www.irs.gov/pub/irs-pdf/p555.pdf    Page 10